AI Detector Insights

Does Grammarly show up as AI? What Turnitin and Grammarly say

Usually not, if you only accept Grammarly's spelling, grammar and punctuation fixes. Turnitin says that in its tests, those changes were not flagged as AI in most cases. Grammarly says its non-generative corrections should typically not affect its own AI score. Text you write or rewrite with Grammarly's generative AI features is different: both say it will likely be flagged.

By HumaniserPublished November 10, 2026Updated November 10, 20269 min read

Facts are as of November 2026: we checked each source on November 10, 2026. Products, help pages and course policies change, so confirm the details for your course.

Which Grammarly features get flagged as AI?

The ones that generate or rewrite text. Turnitin and Grammarly both separate corrections to your own sentences from generative AI that writes new ones.

Grammarly features and what each vendor says about AI flags, as of November 2026
Grammarly feature	Generative AI?	What Turnitin says	What Grammarly says about its own detector
Spelling, grammar and punctuation fixes	No. Grammarly says this underlying AI does not change the substance of your writing.Source: Grammarly	In Turnitin's tests on human-written documents, these changes were not flagged in most cases.Source: Turnitin	Non-generative corrections should typically not affect its AI score.Source: Grammarly
Clarity rewrites and word choice suggestions	No. Grammarly lists them as traditional, non-generative features.Source: Grammarly	Not named. Turnitin's statement covers spelling, grammar and punctuation changes.Source: Turnitin	Non-generative corrections (Grammarly's red and blue underlines) should typically not affect its AI score.Sources: Grammarly: AI Detector user guide (support), Grammarly: Introducing Authorship (support)
Paraphrasing and summarizing	Yes. Grammarly says paraphrasing edits are performed by large language models, and Turnitin lists summarizing among Grammarly's generative features.Sources: Grammarly, Turnitin	Content from these features will likely be flagged as AI-generated.Source: Turnitin	Rewrites from its Paraphraser agent are likely to be flagged by its own detector.Source: Grammarly
Prompted rewrites and drafting (AI assistant, Grammarly agent, AI Chat)	Yes. Grammarly says these optional features can generate content and meaningfully change writing.Sources: Grammarly: Does the use of Grammarly trigger AI detectors? (support), Grammarly: Introducing generative AI assistance (support)	Draft generation is named among the features whose output will likely be flagged.Source: Turnitin	Using the Grammarly agent or AI assistant to meaningfully rewrite sentences and paragraphs will raise its AI score.Source: Grammarly
Humanizer agent	Yes. Grammarly says Humanizer agent rewrites come from its own LLM.Source: Grammarly	Not named. Turnitin says it can identify AI text modified by humanizer tools, in English only.Source: Turnitin	Likely to be flagged as AI-generated by its own detector.Source: Grammarly

Does Grammarly show up as AI on Turnitin?

Not for ordinary grammar checking, according to Turnitin. Its AI writing detection FAQ says the detector “is not tuned to target Grammarly-generated spelling, grammar, and punctuation modifications”. It targets content written by large language models instead. In Turnitin's tests on human-written documents, changes made by Grammarly free and premium, or by other grammar checkers, were not flagged as AI-written in most cases.

There is a clear exception. Turnitin excludes content from Grammarly's generative AI features, “including draft generation, paraphrasing, summarizing, and other features”, and says that content will likely be flagged as AI-generated. Turnitin also says it can identify AI text that was modified by paraphraser or bypasser tools, which it also calls humanizers. That check covers English submissions only.

Two details matter for students. Turnitin's AI indicator and report are not visible to students, though an instructor can download the report as a PDF and share it. And an English submission needs at least 300 words of long-form prose to get an AI score. Our guide to how Turnitin detects AI covers the rest of its system.

Do Grammarly corrections count as AI?

They use AI, but not generative AI. Grammarly describes two layers. Its foundational AI technology makes suggestions for spelling, grammar, clarity, conciseness and tone. Grammarly says it does not change the substance of the writing and cannot be turned off separately from the product.

Its generative AI features arrived in 2023. Grammarly says they are optional and on-demand, and that they “can generate content and meaningfully change writing”. They include prompted rewrites of a selected paragraph, outlining with AI Chat, and the Paraphraser and Humanizer agents named in its AI Detector guide. Any user can turn generative AI off in the Feature customization tab of their account settings.

Whether either layer counts as AI for your course is a policy question, and schools differ. The University at Buffalo tells instructors that Grammarly now includes generative AI that “can suggest heavy re-writes of material and/or create new text”, and asks them to make clear what is acceptable. Eastern Illinois University tells students that Grammarly should not be used without the instructor's prior approval. Read your syllabus and ask if it is unclear. Our responsible AI use guide explains how to disclose AI help when it is allowed.

Why is Grammarly showing up as AI?

Most often because some text came from a generative feature, even if it felt like editing. Grammarly's AI Detector guide says rewrites from its Grammarly, Paraphraser and Humanizer agents come from its own LLM, so its detector will likely flag them. It suggests using the agents for feedback that you apply by hand instead. Grammarly adds that paraphrasing edits from Grammarly and other providers are performed by LLMs, so they should still produce some AI percentage.

Other causes have nothing to do with Grammarly:

Flat or repetitive text. Turnitin says false positives can include text without much structural variation, text that repeats itself, and text paraphrased without developing new ideas.
Short documents. In documents of a few hundred words, Turnitin says its prediction is mostly “all or nothing”, so mixed text can be flagged as entirely AI-generated.
Non-native English writing. A 2023 study found that several GPT detectors “consistently misclassify non-native English writing samples as AI-generated”. Grammarly's own blog says highly structured formal writing, and writing by people who speak English as an additional language, can sometimes resemble AI patterns.

For the patterns detectors react to, see our guides to signs of AI writing and how AI detectors work.

How does Grammarly's AI detector work?

It estimates how much of a text resembles AI writing, section by section. Grammarly's support guide says it breaks your text into smaller sections and checks each one for patterns typical of AI text, such as language patterns, syntax and complexity. It returns the percentage of scanned text that is likely AI-generated. Grammarly says it “cannot provide a definitive conclusion”.

The free AI detector on Grammarly's website takes pasted or uploaded text and shows a percentage after you click Scan for AI. With Grammarly Pro, the AI Detector agent shows which parts may sound AI-generated and helps you add citations. The detector is a proprietary in-house model, and Grammarly says its scores may differ from Turnitin, GPTZero, Copyleaks and others. A Grammarly score is not a preview of what your instructor will see.

Is Grammarly's AI detector accurate?

Grammarly says it scores highly on a public benchmark, and also that no detector, its own included, is 100% accurate. Its AI detector page says it “achieves 99% detection accuracy and ranks #1 on RAID's independent benchmark”. That ranking is Grammarly's own claim. RAID's leaderboard changes as detectors are added: on November 10, 2026 it listed several newer submissions with higher scores than Grammarly's.

RAID is a research benchmark presented at ACL 2024. Its authors wrote that many detectors claim 99% accuracy or more, but few are tested on shared, challenging data. In their own tests of 12 detectors, they found current detectors “easily fooled by adversarial attacks” and by models they had not seen.

RAID's published results for Grammarly's entry, which lists a detector release date of February 9, 2026, show about 99.5% accuracy at a 5% false positive rate and about 98.2% at a 1% rate across all test settings, including adversarial attacks. RAID measures accuracy at a fixed false positive rate, 5% by default. Its test texts come from eight domains: abstracts, books, news, poetry, recipes, Reddit posts, reviews and Wikipedia. Student essays are not among them, so the benchmark does not show how the detector treats your draft.

Grammarly's support guide is more cautious. It calls the model “directionally accurate”, says shorter passages are slightly harder to score, and describes the result as “an average estimate rather than a definitive percentage assessment”. The model is optimized to minimize false positives, Grammarly says, but human writing can still mirror AI patterns, which it expects to be very rare. Its blog on accuracy adds that once AI text is edited, paraphrased or mixed with human writing, results become less predictable. For another writing-tool vendor's detector, see our QuillBot AI detector accuracy guide.

Can Grammarly Authorship prove you wrote it?

It can document how you wrote it, which an AI detector cannot. Grammarly's Authorship guide says it works in Google Docs, Microsoft Word and Grammarly's docs writing surface. In Google Docs and Word, it sorts text as it enters the document: typed directly, pasted from a browser-based source, or pasted from an unknown source. It separates AI-generated text from text you typed and then rephrased with Grammarly's AI, and from text edited with non-generative features such as grammar correction.

The report has three parts. Analytics break down human-typed and sourced text. The report shows your full text, color-coded by source. The replay shows your typing and editing history from start to finish.

Know the limits before you rely on it:

Turn it on first. Grammarly's Canvas guide says Authorship “can't track writing done before you turned it on”. In Google Docs and Word it is off by default.
Allow clipboard access. Without it, pasted text is labeled “Copied from an unknown source”.
It can miss things. Grammarly says it may not capture every case accurately, for example very fast typing, desktop sources where it does not run, or new AI tools not yet categorized. In Word it tracks up to 20 pages reliably.
You decide who sees it. Grammarly says your school cannot see your report unless you create it, make the link shareable and send it. Some instructors require a report for Canvas assignments.
Your data is stored. Grammarly's Authorship guide says Authorship data sent when you open a report can stay on Grammarly's servers for up to 10 years.

Grammarly also tells faculty that Authorship should not be used as “a single data point” to penalize students.

Check your draft before you submit

Humaniser's free AI detector gives you 30 checks a day with no account. It is a free first check, not an official Turnitin or Grammarly result, so scores can differ.

Use it to find passages worth a second look, then revise them in your own words and keep your drafts. If your course allows Grammarly's generative features, follow its disclosure rules.

What to do if you're flagged after using Grammarly

Treat a flag as the start of a review, not a verdict. Turnitin says its AI percentage “should not be used as the sole basis for action”, and that the final decision on misconduct rests with the instructor. Grammarly calls AI detectors “a single data point rather than the sole source of evidence”.

Ask what was flagged. Ask which tool produced the score and which passages it highlighted. You can't see Turnitin's AI report yourself, but your instructor can download it as a PDF and share it.
List the Grammarly features you used. Accepting spelling fixes is not the same as accepting a paragraph rewrite or a paraphrase. The table above shows how each vendor treats each one.
Gather evidence of your process. Share an Authorship report if you had it on. In Google Docs, version history lets anyone with edit access browse earlier versions of the file. Add your outline, notes and sources.
Explain honestly. If you used a generative feature, say so, and point to what your course policy allowed.

Our guide to AI detector false positives includes an appeal template. If you also got a similarity score, our AI detector vs plagiarism checker guide explains how the two reports differ.

Common questions

Can Turnitin detect Grammarly?

Not for grammar checking. Turnitin says its detector is not tuned to target Grammarly's spelling, grammar and punctuation changes, which in most cases were not flagged in its tests. Output from Grammarly's generative features, such as draft generation, paraphrasing and summarizing, will likely be flagged.Source: Turnitin

Does Grammarly Pro show up as AI?

The feature matters more than the plan. Turnitin's statement covers Grammarly free and premium: grammar-checking changes were mostly not flagged, while output from generative features will likely be flagged. Grammarly draws the same line for its own detector.Sources: Turnitin, Grammarly

Is using Grammarly cheating?

It depends on your course. The University at Buffalo leaves tool choices to instructors, and Eastern Illinois University tells students not to use Grammarly without the instructor's prior approval. Grammarly also tells students to follow their institution's AI policies. Check your syllabus or ask.Sources: University at Buffalo, Eastern Illinois University, Grammarly

Is Grammarly's AI detector free?

Yes. Grammarly's website has a free AI detector: paste or upload text, click Scan for AI and you get a percentage. Grammarly Pro adds the AI Detector agent, which shows which parts may sound AI-generated.Source: Grammarly

Can Turnitin detect Grammarly's humanizer?

Turnitin does not name Grammarly's Humanizer, but says it can identify AI-generated text modified by paraphraser or humanizer tools in English submissions. Grammarly says rewrites from its Humanizer agent come from its LLM, and its own detector will likely flag them.Sources: Turnitin, Grammarly

Is Grammarly's AI detector as accurate as Turnitin?

We did not find a published study that tests the two side by side on the same student essays. RAID's public list of leaderboard submissions includes Grammarly but not Turnitin. Grammarly says its scores may differ from Turnitin's, so do not treat its result as the score your instructor will see.Sources: RAID benchmark, Grammarly

Sources

Checked on November 10, 2026. Vendor pages describe each vendor's own product, and accuracy figures are the vendor's or the benchmark's, not ours.

Does Turnitin detect AI? How the score works and its limits
Yes, if your school licenses it. What Turnitin's AI detector flags and skips, what the score and asterisk mean, how accurate it is and what to do if flagged.
Is QuillBot's AI detector accurate? What QuillBot, Turnitin and studies say
Is QuillBot's AI detector accurate? What QuillBot says about its scores and limits, what studies found on paraphrased text, and why it can't predict Turnitin.
AI Detector False Positives: How to Prove You Wrote It
Flagged as AI for writing you did yourself? Learn why detectors like GPTZero and Turnitin get it wrong, how to reduce false positives and how to appeal.
AI detector vs plagiarism checker: what the scores mean
AI detector vs plagiarism checker: understand low similarity and high AI scores, compare four example reports, and review sources and writing evidence fairly.