{"id":9945,"date":"2025-06-01T12:20:52","date_gmt":"2025-06-01T12:20:52","guid":{"rendered":"https:\/\/undetectable.ai/blog\/?p=9945"},"modified":"2025-06-27T13:16:23","modified_gmt":"2025-06-27T13:16:23","slug":"grammarly-ai-checker","status":"publish","type":"post","link":"https:\/\/undetectable.ai/blog\/grammarly-ai-checker\/","title":{"rendered":"Grammarly AI Checker Review: Is It Accurate?"},"content":{"rendered":"\n<p>In August 2024, Grammarly launched its AI content detector after calling AI checkers <strong>&#8220;unreliable.&#8221;<\/strong><\/p>\n\n\n\n<p>Grammarly is trusted by over 30 million people around the world.&nbsp;<\/p>\n\n\n\n<p>It is well-known for helping with spelling, grammar, style, and tone on many devices and platforms.&nbsp;<\/p>\n\n\n\n<p>Because of this, people were excited when Grammarly added a tool to detect AI-written content.<\/p>\n\n\n\n<p>Now we have to check, do AI Checker of Grammarly solve the problems they once criticized?<\/p>\n\n\n\n<p>Is Grammarly AI checker accurate?<\/p>\n\n\n\n<p>Or we&#8217;ll be specific.<\/p>\n\n\n\n<p>Is Grammarly AI checker reliable?<\/p>\n\n\n\n<p>In this blog, we&#8217;ll test Grammarly&#8217;s AI checker across six different content types to see how well it actually works. <\/p>\n\n\n\n<p>We&#8217;ll show you exactly where it succeeds, where it fails, and whether you can trust it for your content verification needs.&nbsp;<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p class=\"has-text-align-center\"><strong>Key Takeaways<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Grammarly&#8217;s AI checker achieved only 33% accuracy in our tests across 6 types of content.<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The tool correctly identified 100% human content but failed to detect fully AI-generated text.<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Is Grammarly AI checker accurate?<\/strong> Based on our testing, the detector struggles with paraphrased AI content and mixed human-AI writing.<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Free users have a limit of 1,000 words per submission, whereas premium users have higher limits.<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>More specialized tools like <a href=\"https:\/\/undetectable.ai\/\" target=\"_blank\" rel=\"noreferrer noopener\">Undetectable AI&#8217;s detector<\/a> (100% accuracy) are much more reliable than the Grammarly AI checker free version.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">What Is the Grammarly AI Checker?<\/h2>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-1024x683.avif 1024w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-300x200.avif 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-768x512.avif 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-18x12.avif 18w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008.avif 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-1024x683.webp 1024w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-300x200.webp 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-768x512.webp 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-18x12.webp 18w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-1024x683.jpg\" height=\"683\" width=\"1024\" srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-1024x683.jpg 1024w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-300x200.jpg 300w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-768x512.jpg 768w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008-18x12.jpg 18w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/Grammarly-AI-Checker-0008.jpg 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" class=\"wp-image-9951 sp-no-webp\" alt=\"Illustrated image of a young woman writing with a pen as floating letters appear around her\" loading=\"lazy\" decoding=\"async\"  > <\/picture><\/figure><\/div>\n\n\n<p>Grammarly AI Checker is designed to help you spot whether a piece of writing might have been generated by AI.&nbsp;<\/p>\n\n\n\n<p>The detector is built right into <strong>Grammarly\u2019s existing platform<\/strong>, so it works alongside their grammar, spelling and style tools.&nbsp;<\/p>\n\n\n\n<p>Here\u2019s how Grammarly AI checker rollout went:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>August 2024: <\/strong>Official launch of the AI detector<\/li>\n\n\n\n<li><strong>September 2024: <\/strong>Beta version released for Google Docs<\/li>\n\n\n\n<li><strong>Early 2025: <\/strong>More features on the way, especially for educators<\/li>\n<\/ul>\n\n\n\n<p>This feature is a part of Grammarly\u2019s broader push for <strong>\u201cGrammarly Authorship.\u201d I<\/strong>t\u2019s their way of taking a stand for authentic, human writing in an age where AI is everywhere.<\/p>\n\n\n\n<p>Who is this tool for?<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Students and teachers.<\/li>\n\n\n\n<li>Content creators and marketers.<\/li>\n\n\n\n<li>Professional writers.<\/li>\n<\/ul>\n\n\n\n<p>Since the detector is part of Grammarly\u2019s main platform, it\u2019s much easier to use than separate <strong>AI-checking tools.&nbsp;<\/strong><\/p>\n\n\n\n<p>If you&#8217;re already using Grammarly, this feature fits right into your workflow\u2014no need to copy and paste into another website.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Key Features of Grammarly\u2019s AI Detector<\/h3>\n\n\n\n<p>Here are the standout features of Grammarly AI checker:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Grammarly AI checker free<strong> <\/strong>plan analyzes up to 1,000 words. Premium offers higher limits and more tools.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Fully embedded in Grammarly\u2019s web, desktop, and mobile apps\u2014no extra tools needed.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Shows a percentage likelihood of AI-generated content.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Works on browser extensions, desktop apps, and mobile devices.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Detects AI content instantly as you write.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How Grammarly\u2019s AI Checker Works<\/h2>\n\n\n\n<p>Grammarly AI checker work by spotting patterns that are common in AI-written content.&nbsp;<\/p>\n\n\n\n<p>It looks at things like how sentences are built, the style of writing, and repeated language structures.<\/p>\n\n\n\n<p>The tool uses machine learning.&nbsp;<\/p>\n\n\n\n<p>That means it has been trained on lots of examples to recognize what AI writing usually looks like.&nbsp;<\/p>\n\n\n\n<p>Grammarly says they use \u201crigorous testing\u201d to make sure the tool is directionally accurate\u2014good at spotting likely AI, even if not perfect.<\/p>\n\n\n\n<p>But how reliable is Grammarly AI checker performance in practice? It works best with longer texts. <\/p>\n\n\n\n<p>Short passages don\u2019t give it enough data to analyze, so the results may be less accurate.<\/p>\n\n\n\n<p>Because it\u2019s built into Grammarly\u2019s platform, it also uses the same systems that check grammar and style.&nbsp;<\/p>\n\n\n\n<p>This helps it understand the overall flow of your writing.&nbsp;<\/p>\n\n\n\n<p>But there\u2019s a downside\u2014since it\u2019s not a dedicated AI detector, it may miss things that specialized tools are better at catching.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Is Grammarly AI Checker Accurate?<\/h2>\n\n\n\n<p>To evaluate Grammarly AI checker is accurate or not, we used <a href=\"https:\/\/www.zdnet.com\/article\/i-tested-10-ai-content-detectors-and-these-5-correctly-identified-ai-text-every-time\/\" target=\"_blank\" rel=\"noreferrer noopener\">ZDNet&#8217;s framework<\/a>. <\/p>\n\n\n\n<p>This methodology analyzes six distinct content categories to measure real-world performance.<\/p>\n\n\n\n<p><strong>The Test: 6 Categories of Content<\/strong><\/p>\n\n\n\n<p>We tested the AI checker Grammarly provides against six types of content:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Category<\/strong><\/td><td><strong>Content Type<\/strong><\/td><\/tr><tr><td>1<\/td><td>100% AI<\/td><\/tr><tr><td>2<\/td><td>100% Human<\/td><\/tr><tr><td>3<\/td><td>Lightly Edited AI<\/td><\/tr><tr><td>4<\/td><td>Paraphrased AI<\/td><\/tr><tr><td>5<\/td><td>Mixed Human + AI<\/td><\/tr><tr><td>6<\/td><td>AI with Plagiarism<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>Let&#8217;s see how Grammarly AI checker performed under each category:<\/p>\n\n\n\n<p><strong>Category 1: 100% AI<\/strong><\/p>\n\n\n\n<p><strong>Reality:<\/strong> Fully AI-generated<br><strong>Grammarly Result: <\/strong>50% AI<br><strong>Verdict: <\/strong>Incorrect Detection<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-1024x338.avif 1024w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-300x99.avif 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-768x253.avif 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-18x6.avif 18w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001.avif 1085w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-1024x338.webp 1024w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-300x99.webp 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-768x253.webp 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-18x6.webp 18w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001.webp 1085w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-1024x338.jpg\" height=\"338\" width=\"1024\" srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-1024x338.jpg 1024w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-300x99.jpg 300w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-768x253.jpg 768w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001-18x6.jpg 18w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-001.jpg 1085w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" class=\"wp-image-9952 sp-no-webp\" alt=\"\" loading=\"lazy\" decoding=\"async\"  > <\/picture><\/figure><\/div>\n\n\n<p>This content was generated entirely by ChatGPT with zero human editing. <\/p>\n\n\n\n<p>The AI Grammarly checker should have flagged this as highly AI-generated, but it only detected 50% AI probability.<\/p>\n\n\n\n<p><strong>Category 2: 100% Human (Classic Advertisement)<\/strong><\/p>\n\n\n\n<p><strong>Reality: <\/strong>Human-written<br><strong>Grammarly Result:<\/strong> 0% AI (100% Human)<br><strong>Verdict: <\/strong>Correct Detection<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large\"><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-1024x511.avif 1024w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-300x150.avif 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-768x383.avif 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-18x9.avif 18w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002.avif 1124w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-1024x511.webp 1024w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-300x150.webp 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-768x383.webp 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-18x9.webp 18w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002.webp 1124w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-1024x511.jpg\" height=\"511\" width=\"1024\" srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-1024x511.jpg 1024w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-300x150.jpg 300w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-768x383.jpg 768w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002-18x9.jpg 18w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-002.jpg 1124w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" class=\"wp-image-9953 sp-no-webp\" alt=\"\" loading=\"lazy\" decoding=\"async\"  > <\/picture><\/figure><\/div>\n\n\n<p>The content was written decades before AI tools existed. The Grammarly AI checker correctly identified this as entirely human-written.<\/p>\n\n\n\n<p><strong>Category 3: Lightly Edited AI<\/strong><\/p>\n\n\n\n<p><strong>Reality:<\/strong> Primarily AI with minimal human edits<br><strong>Grammarly Result: <\/strong>25% AI<br><strong>Verdict:<\/strong> Incorrect Detection<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003-.avif 1020w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003--300x160.avif 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003--768x410.avif 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003--18x10.avif 18w\" sizes=\"auto, (max-width: 1020px) 100vw, 1020px\" type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003-.webp 1020w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003--300x160.webp 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003--768x410.webp 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003--18x10.webp 18w\" sizes=\"auto, (max-width: 1020px) 100vw, 1020px\" type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003-.jpg\" height=\"545\" width=\"1020\" srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003-.jpg 1020w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003--300x160.jpg 300w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003--768x410.jpg 768w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-003--18x10.jpg 18w\" sizes=\"auto, (max-width: 1020px) 100vw, 1020px\" class=\"wp-image-9954 sp-no-webp\" alt=\"\" loading=\"lazy\" decoding=\"async\"  > <\/picture><\/figure><\/div>\n\n\n<p>Only 20-25% of this content received human editing. The AI checker Grammarly significantly underestimated the AI involvement.<\/p>\n\n\n\n<p><strong>Category 4: Paraphrased AI Content<\/strong><\/p>\n\n\n\n<p><strong>Reality: <\/strong>AI origin, paraphrased to sound human<br><strong>Grammarly Result: <\/strong>33% AI<br><strong>Verdict:<\/strong> Correct Detection<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004.avif 974w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004-300x164.avif 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004-768x421.avif 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004-18x10.avif 18w\" sizes=\"auto, (max-width: 974px) 100vw, 974px\" type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004.webp 974w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004-300x164.webp 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004-768x421.webp 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004-18x10.webp 18w\" sizes=\"auto, (max-width: 974px) 100vw, 974px\" type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004.jpg\" height=\"534\" width=\"974\" srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004.jpg 974w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004-300x164.jpg 300w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004-768x421.jpg 768w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-004-18x10.jpg 18w\" sizes=\"auto, (max-width: 974px) 100vw, 974px\" class=\"wp-image-9955 sp-no-webp\" alt=\"\" loading=\"lazy\" decoding=\"async\"  > <\/picture><\/figure><\/div>\n\n\n<p>This content was originally AI-generated, then paraphrased using humanization tools. The Grammarly AI checker detected some AI traces.<\/p>\n\n\n\n<p><strong>Category 5: Mixed Human + AI Content<\/strong><\/p>\n\n\n\n<p><strong>Reality: <\/strong>50% human writing + 50% AI-generated phrases<br><strong>Grammarly Result: <\/strong>20% AI<br><strong>Verdict: <\/strong>Incorrect Detection<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005-.avif 984w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005--300x156.avif 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005--768x400.avif 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005--18x9.avif 18w\" sizes=\"auto, (max-width: 984px) 100vw, 984px\" type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005-.webp 984w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005--300x156.webp 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005--768x400.webp 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005--18x9.webp 18w\" sizes=\"auto, (max-width: 984px) 100vw, 984px\" type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005-.jpg\" height=\"512\" width=\"984\" srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005-.jpg 984w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005--300x156.jpg 300w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005--768x400.jpg 768w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-005--18x9.jpg 18w\" sizes=\"auto, (max-width: 984px) 100vw, 984px\" class=\"wp-image-9956 sp-no-webp\" alt=\"\" loading=\"lazy\" decoding=\"async\"  > <\/picture><\/figure><\/div>\n\n\n<p>With equal parts human and AI content, the AI Grammarly checker should have detected around 50% AI involvement, not 20%.<\/p>\n\n\n\n<p><strong>Category 6: AI with Plagiarism<\/strong><\/p>\n\n\n\n<p><strong>Reality: <\/strong>AI-written with factual historical overlap<br><strong>Grammarly Result: <\/strong>25% AI<br><strong>Verdict:<\/strong> Incorrect Detection<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006.avif 986w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006-300x155.avif 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006-768x398.avif 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006-18x9.avif 18w\" sizes=\"auto, (max-width: 986px) 100vw, 986px\" type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006.webp 986w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006-300x155.webp 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006-768x398.webp 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006-18x9.webp 18w\" sizes=\"auto, (max-width: 986px) 100vw, 986px\" type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006.jpg\" height=\"511\" width=\"986\" srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006.jpg 986w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006-300x155.jpg 300w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006-768x398.jpg 768w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-006-18x9.jpg 18w\" sizes=\"auto, (max-width: 986px) 100vw, 986px\" class=\"wp-image-9957 sp-no-webp\" alt=\"\" loading=\"lazy\" decoding=\"async\"  > <\/picture><\/figure><\/div>\n\n\n<p>This was fully AI-generated content that happened to include some historically accurate information. The Grammarly AI checker missed the AI generation entirely.<\/p>\n\n\n\n<p><strong>Final Scorecard<\/strong><\/p>\n\n\n\n<p>Out of 6 total test cases:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Correct Detections:<\/strong> 2 (Categories 2 and partially 4)<\/li>\n\n\n\n<li><strong>False Positives\/Negatives: <\/strong>4 (Categories 1, 3, 5, 6)<\/li>\n<\/ul>\n\n\n\n<p><strong>Detection Accuracy: <\/strong>33%<\/p>\n\n\n\n<p>The Grammarly AI checker shows limited reliability, accurately identifying content only one-third of the time. <\/p>\n\n\n\n<p>While it excels at recognizing purely human content, it consistently underestimates AI involvement across all other categories.<\/p>\n\n\n\n<p>This performance highlights a critical issue: the AI checker Grammarly isn&#8217;t just unreliable\u2014it&#8217;s dangerously misleading for users who need accurate AI detection.<\/p>\n\n\n\n<p>So for your own content verification\u2026&nbsp;<\/p>\n\n\n\n<p>Use <a href=\"https:\/\/undetectable.ai\/\" target=\"_blank\" rel=\"noreferrer noopener\">Undetectable AI Detector<\/a> to get 100% accurate results. In ZDNet\u2019s own testing, this AI detector has correctly identified all six categories without false positives and negatives.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007.avif 847w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007-300x220.avif 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007-768x563.avif 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007-16x12.avif 16w\" sizes=\"auto, (max-width: 847px) 100vw, 847px\" type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007.webp 847w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007-300x220.webp 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007-768x563.webp 768w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007-16x12.webp 16w\" sizes=\"auto, (max-width: 847px) 100vw, 847px\" type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007.jpg\" height=\"621\" width=\"847\" srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007.jpg 847w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007-300x220.jpg 300w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007-768x563.jpg 768w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/06\/AI-Checker-007-16x12.jpg 16w\" sizes=\"auto, (max-width: 847px) 100vw, 847px\" class=\"wp-image-9958 sp-no-webp\" alt=\"\" loading=\"lazy\" decoding=\"async\"  > <\/picture><\/figure><\/div>\n\n\n<p>You can also apply our <a href=\"https:\/\/undetectable.ai\/ai-humanizer\" target=\"_blank\" rel=\"noreferrer noopener\">Undetectable AI Humanizer<\/a> to rewrite any flagged sections until they appear genuinely human.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><picture><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer.avif 640w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer-300x150.avif 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer-18x9.avif 18w\" sizes=\"auto, (max-width: 640px) 100vw, 640px\" type=\"image\/avif\"><source srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer.webp 640w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer-300x150.webp 300w,https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer-18x9.webp 18w\" sizes=\"auto, (max-width: 640px) 100vw, 640px\" type=\"image\/webp\"><img src=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer.jpg\" height=\"321\" width=\"640\" srcset=\"https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer.jpg 640w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer-300x150.jpg 300w, https:\/\/undetectable.ai/blog\/wp-content\/uploads\/2025\/05\/AI-Humanizer-18x9.jpg 18w\" sizes=\"auto, (max-width: 640px) 100vw, 640px\" class=\"wp-image-9653 sp-no-webp\" alt=\"Screenshot of Advanced AI Humanizer from Undetectable AI tool interface\" loading=\"lazy\" decoding=\"async\"  > <\/picture><\/figure><\/div>\n\n\n<p>Re-test with multiple detectors to confirm your content passes across different platforms<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Grammarly AI Checker Weaknesses and Limitations<\/h3>\n\n\n\n<p>Here are the main ways Grammarly\u2019s AI checker doesn\u2019t quite hit the mark:<\/p>\n\n\n\n<p><strong>Accuracy Issues<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>It sometimes overlooks content that is clearly written by AI.<\/li>\n\n\n\n<li>When it gives low AI scores, it can make you think the content is more original than it really is.<\/li>\n\n\n\n<li>The results are not consistent &#8211; accuracy changes based on the type of content and which AI model created it.<\/li>\n<\/ul>\n\n\n\n<p><strong>Technical Limitations<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Free users can only scan up to 1,000 words at a time.<\/li>\n\n\n\n<li>It\u2019s optimized for English and doesn\u2019t handle other languages well.<\/li>\n\n\n\n<li>Casual, creative, or informal writing can confuse it.<\/li>\n\n\n\n<li>It tends to slow down when analyzing longer texts.<\/li>\n<\/ul>\n\n\n\n<p><strong>Practical Drawbacks<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>You can\u2019t upload or check multiple documents in one go.<\/li>\n\n\n\n<li>It doesn\u2019t differentiate between AI-edited and AI-written content.<\/li>\n<\/ul>\n\n\n\n<p><strong>Core Challenges<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The tool is struggling to keep pace with how quickly AI is evolving.<\/li>\n\n\n\n<li>Newer AI models can easily slip past its detection.<\/li>\n\n\n\n<li>Mixed content\u2014where humans edit or expand on AI output\u2014often flies under the radar.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Grammarly AI Checker vs. Other AI Detectors<\/h2>\n\n\n\n<p>When it comes to AI detection accuracy, Grammarly\u2019s AI checker struggles to keep up with tools specifically designed for this task. <\/p>\n\n\n\n<p>Here&#8217;s how the top detectors performed in our testing:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Tool<\/strong><\/td><td><strong>Accuracy<\/strong><\/td><td><strong>Standout Feature<\/strong><\/td><td><strong>Weakness<\/strong><\/td><td><strong>Price\/Month<\/strong><\/td><\/tr><tr><td>Grammarly<\/td><td>33%<\/td><td>Seamless integration with writing platform<\/td><td>Dangerously low accuracy rates<\/td><td>$12<\/td><\/tr><tr><td>Undetectable AI<\/td><td>100%<\/td><td>AI humanizer to bypass detectors<\/td><td>Limited free usage<\/td><td>$19<\/td><\/tr><tr><td>Copyleaks<\/td><td>50-80%<\/td><td>Multilingual support (30+ languages)<\/td><td>Less precise with newer AI models<\/td><td>$17<\/td><\/tr><tr><td>GPT Zero<\/td><td>100%<\/td><td>Sentence-by-sentence AI probability scoring<\/td><td>Limited free tier<\/td><td>$15<\/td><\/tr><tr><td>StealthWriter AI<\/td><td>50%<\/td><td>Rewrites AI text to appear human-written<\/td><td>May alter original meaning<\/td><td>$20<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><strong>Note: <\/strong>We&#8217;ve conducted comprehensive reviews of both <a href=\"https:\/\/undetectable.ai\/blog\/copyleaks-review\/\" target=\"_blank\" rel=\"noreferrer noopener\">Copyleaks<\/a> and <a href=\"https:\/\/undetectable.ai\/blog\/stealthwriter-ai-review\/\" target=\"_blank\" rel=\"noreferrer noopener\">StealthWriter AI<\/a> using the same testing methodology.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Can Grammarly Detect AI-Edited or Paraphrased Text?<\/h2>\n\n\n\n<p>This is where the AI checker Grammarly shows its biggest weaknesses.<\/p>\n\n\n\n<p><strong>Paraphrased AI Content Performance<\/strong><\/p>\n\n\n\n<p>In our testing, Grammarly AI Checker detected only 33% AI in content that was originally 100% AI-generated but paraphrased using humanization tools.<\/p>\n\n\n\n<p>This means that anyone using AI paraphrasing tools or AI humanizer software can easily bypass Grammarly AI Checker detection.<\/p>\n\n\n\n<p><strong>AI-Edited Content Challenges<\/strong><\/p>\n\n\n\n<p>The AI Grammarly checker struggles even more with AI-edited content\u2014text that starts human but receives AI enhancement or expansion.<\/p>\n\n\n\n<p>Our<strong> &#8220;lightly edited AI&#8221; <\/strong>category showed only 25% AI detection when the reality was 75-80% AI involvement.<\/p>\n\n\n\n<p>Tools like <a href=\"https:\/\/undetectable.ai\/ai-humanizer\" target=\"_blank\" rel=\"noreferrer noopener\">Undetectable AI&#8217;s humanizer<\/a> and <a href=\"https:\/\/undetectable.ai\/paraphrasing-tool\" target=\"_blank\" rel=\"noreferrer noopener\">AI paraphraser<\/a> are specifically designed to evade detection. <\/p>\n\n\n\n<p>In <a href=\"https:\/\/undetectable.ai\/blog\/stealthwriter-ai-review\/\" target=\"_blank\" rel=\"noreferrer noopener\">our last review<\/a>, we tested the accuracy of the humanizer tools, and our testing showed:<\/p>\n\n\n\n<p><strong>StealthWriter AI: <\/strong>Reduced AI detection from 100% to 5% across multiple detectors.<br><strong>Undetectable AI: <\/strong>Achieved 1% AI detection after humanization<br><strong>Quillbot Paraphrasing: <\/strong>Still showed 76% AI detection (less effective)<\/p>\n\n\n\n<p><strong>The Bottom Line: <\/strong>If someone wants to bypass Grammarly AI Checker, readily available tools make it trivially easy.<\/p>\n\n\n\n<p>Access our AI Detector and Humanizer directly through the widget below.<\/p>\n\n\n\n<div id=\"uai-widget\" data-affiliate-link=\"https:\/\/undetectable.ai\/?_by=hi4km\"><script>var js = document.createElement(\"script\");js.async = true;js.src = \"https:\/\/widget.undetectable.ai\/js\/widget-loader.js?t=\"+Date.now();document.getElementsByTagName(\"head\")[0].appendChild(js);<\/script><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">FAQs About Grammarly AI Checker<\/h2>\n\n\n<div id=\"rank-math-faq\" class=\"rank-math-block\">\n<div class=\"rank-math-list \">\n<div id=\"faq-question-1749212938475\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Can Grammarly flag GPT-4 content?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Not reliably. The AI checker Grammarly often says GPT-4 content is less AI when it&#8217;s actually fully AI. <\/p>\n<p>It has trouble spotting text from advanced tools like GPT-4.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1749212951509\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">How does Grammarly compare with Turnitin or GPTZero?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Grammarly is more user-friendly but far less accurate. In our tests, Grammarly scored just 33%. <\/p>\n<p>GPTZero showed 99.8% accuracy, while Turnitin scored between 87\u201390% in other independent tests. If accuracy is your priority, Grammarly falls short.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1749212963614\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Can Grammarly\u2019s detection results be wrong?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Yes\u2014frequently. The Grammarly AI checker<strong> <\/strong>underdetects AI content and may falsely reassure users that AI-generated text is original. <\/p>\n<p>It also flags some human-written technical content incorrectly.<\/p>\n\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\">Conclusion<\/h2>\n\n\n\n<p>The Grammarly AI checker is easy to use because it\u2019s built into the Grammarly platform, but our tests show that it\u2019s not very accurate.&nbsp;<\/p>\n\n\n\n<p>It was accurate 33% of the time. This means it frequently misses AI-generated content or gives incorrect results.<\/p>\n\n\n\n<p>So, is the Grammarly AI checker accurate enough?&nbsp;<\/p>\n\n\n\n<p>If you just need a quick and simple check inside Grammarly, it might work.&nbsp;<\/p>\n\n\n\n<p>If you truly need to determine whether something was written by AI, this tool alone isn\u2019t sufficient\u2014there are other options that perform much better.<\/p>\n\n\n\n<p>The free version of the Grammarly AI checker lets you check short texts, and the paid version gives more features\u2014but neither one fixes the accuracy problem.&nbsp;<\/p>\n\n\n\n<p>If you need to trust the results, it\u2019s better to use reliable tools like <a href=\"https:\/\/undetectable.ai\/\" target=\"_blank\" rel=\"noreferrer noopener\">Undetectable AI Detector<\/a> for 100% accuracy.&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":15,"featured_media":9950,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_themeisle_gutenberg_block_has_review":false,"footnotes":""},"categories":[5],"tags":[],"class_list":["post-9945","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-reviews"],"_links":{"self":[{"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/posts\/9945","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/comments?post=9945"}],"version-history":[{"count":7,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/posts\/9945\/revisions"}],"predecessor-version":[{"id":10061,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/posts\/9945\/revisions\/10061"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/media\/9950"}],"wp:attachment":[{"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/media?parent=9945"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/categories?post=9945"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/undetectable.ai/blog\/wp-json\/wp\/v2\/tags?post=9945"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}