Is Grammarly AI? When Grammarly Counts as AI Writing, and When It Does Not

Is Grammarly AI? Yes, and that is the wrong question to stop at. Grammarly runs on AI, but it offers two very different kinds of help: suggestions that correct spelling, grammar and punctuation in text you wrote, and generative features that compose, rewrite and draft text for you. Detectors, teachers and honor codes draw their lines between those two, not around the brand name. This page sorts Grammarly's features by type, shows what Turnitin says its detector does with each, quotes two university policies that handle editing tools in opposite ways, and walks one paragraph through both kinds of help.

Is Grammarly AI? Two kinds of help in one tool

The question is never the brand. It is which button you pressed.

Grammarly's own help center splits its AI into layers. Its guide to generative AI assistance says the on-demand generative feature helps you "compose, rewrite, ideate, and reply": you select text, click the pencil or lightbulb icon, and Grammarly suggests new wording, or you prompt it to change the text "in any way you prefer." The same page describes AI Chat on Mac and a Write with generative AI tab in the Grammarly Editor that can produce an outline or ideas, and a proactive assistant called Superhuman Go that can "draft content" and "polish existing text."

None of that is the red underline under a misspelled word. The correction layer proposes small fixes to sentences you already wrote; the generative layer produces new sentences. Both are AI in the broad sense. Only the second writes for you.

Will Grammarly be detected as AI?

Turnitin answers this directly in its FAQ on AI writing detection. Asked whether Grammarly grammar checks get flagged as AI, it says no: its detector "is not tuned to target Grammarly-generated spelling, grammar, and punctuation modifications" and that, in tests Turnitin ran on human-written documents, changes made by Grammarly (free and premium) and other grammar checkers were in most cases not flagged. The same answer then carves out content from "Grammarly's generative AI-powered features, including draft generation, paraphrasing, summarizing, and other features," which it says "will likely be flagged as AI-generated."

The paraphrasing section of the same FAQ adds that Turnitin tested popular text spinners, Grammarly's free paraphraser among them, and that AI-generated text run through them is identified as likely AI-paraphrased. Note the order: the paraphrase check only runs on passages the first model already marked as AI-generated. A human paragraph that you paraphrase with a tool is a different case, and Turnitin's FAQ also lists "text that has been paraphrased without developing new ideas" among the things that can trip false positives.

The FAQ also says the detector needs at least 300 words of prose, and that in documents of a few hundred words its prediction is "mostly all or nothing," so a mix of your sentences and rewritten ones can be flagged as entirely AI-generated. Other detectors work differently and disagree with one another; what an AI text detector can and cannot tell you covers the general limits, and how Turnitin's AI indicator works covers the score display in detail.

Does Grammarly count as AI under school rules?

Detectors only estimate. The rule that decides your case is your course policy, and published policies disagree on editing tools. Two examples, both read today:

• Stanford, permissive on surface edits. Stanford's generative AI policy guidance, adopted October 15, 2026, sets a default for courses with no written AI policy: students may use AI "to perform surface-level editing that does not materially alter the substance, analysis, organization, or argument of the work," with correcting spelling, grammar, punctuation and formatting as the examples. Under that default, disclosure of those permitted uses "is not necessary." Using AI to create deliverables such as essays is not permitted, and any other AI use must be documented and disclosed.
• Princeton, strict on disclosure. Princeton's list of academic integrity violations says that, where an instructor permits generative AI, students must disclose its use rather than cite it, and it counts "failing to disclose its use (including the use of generative AI for rewording, paraphrasing or editing)" as a violation. Under that wording, a kept generative rewrite needs a disclosure.

Stanford's guidance also puts a duty on students to "learn about the AI capabilities in any software that they choose to use for coursework" so they can disable or enable them as a course requires. Grammarly is exactly that kind of software: the free checker and the generative assistant sit in the same sidebar. If you are unsure which side a feature falls on, the honest move is to disclose it, and how to write a short AI disclosure statement gives wording you can adapt.

A worked example: one sentence, two kinds of help

Here is an example sentence written for this page, the kind a student might type in a history essay, followed by the two kinds of change Grammarly can make to it.

• Original (example): "The new law were meant to protect workers but it's effect was the opposite, wages fell in most mill towns."
• Correction suggestions (example): "The new law was meant to protect workers, but its effect was the opposite: wages fell in most mill towns." Four small fixes. Every word choice, the claim and the structure are still the student's.
• Generative rewrite (example): "Although the legislation was designed to safeguard laborers, it ultimately produced the reverse outcome, with wages declining across most mill communities." Same idea, new sentence. The vocabulary, rhythm and structure now come from the tool.

Under Stanford's default, the second version is surface-level editing and needs no disclosure. The third is a judgment call at best, and under Princeton's wording it needs a disclosure. Under Turnitin's FAQ, the second is the kind of change it says is usually not flagged, and the third is the kind it says will likely be flagged.

How to use Grammarly without breaking an AI rule

1. Read the policy first

   Find the AI section of the syllabus or assignment sheet, then the school's default. If both are silent, ask the instructor in writing.

2. Turn off what you may not use

   If generative help is banned, switch off or ignore the rewrite, compose and chat features for that assignment. Accept only the underlined correction suggestions.

3. Write the draft yourself, then check it

   Run Grammarly over finished paragraphs, so the ideas, order and wording stay yours.

4. Keep the history

   Draft in a tool with version history so you can show how the text grew. Using version history as an authorship record explains what to save.

5. Disclose anything generative

   If you kept a rewritten sentence, a generated outline or a paraphrase, say so in one or two plain lines, even if the policy is unclear.

Some students also run a finished draft through a second detector before submitting, to see whether any passage reads as machine-written. Walter Writes AI's AI detector is one option: Walter Writes AI is an AI humanizer with a built-in AI detector that supports over 80 languages, and every plan includes voice matching and the detector. Treat its result as one more opinion. No detector, Walter's included, can guarantee 100% accuracy, different detectors often disagree about the same paragraph, and none of them can tell your instructor which Grammarly button you pressed.

Pitfalls

• Accepting every suggestion. A run of accepted rewrites turns your paragraph into the tool's paragraph. Accept corrections; read rewrites as proposals.
• Pasting chatbot text into Grammarly. Polishing AI-generated text does not make it yours. Turnitin's FAQ says AI text passed through Grammarly's paraphraser is likely flagged as AI-paraphrased.
• Treating a clean detector score as permission. A score is an estimate about the text, not a ruling about the policy.

Expert tips

• Name features, not brands, in a disclosure. "Grammarly spelling and grammar suggestions only" tells a reader far more than "I used Grammarly."
• Highlight what changed. Mark any sentence a tool rewrote in one color in your working copy, so you can find it, reread it and disclose it.

Where the line falls is a policy question; AI plagiarism and unauthorized assistance covers it. To make an edited draft sound like you again, see rewriting highlighted passages in your own voice.

Grammarly is AI, but the useful question is which part of it you used. Correction suggestions on your own sentences are treated as editing by Turnitin and by permissive policies such as Stanford's default. Generative rewrites, drafts and paraphrases are treated as AI writing and, under policies like Princeton's, need disclosure. Read the rule, use only what it allows, keep your drafts, and disclose anything the tool wrote. More guides on checking and editing AI writing are on the AI writing hub.