Does Grammarly Count as AI Writing in 2026? We Tested 5 AI Detectors

Grammarly is everywhere. Students use it to polish essays, writers use it to clean up drafts, and professionals use it to tighten emails. But as Grammarly adds more AI features, a question keeps coming up: does using Grammarly count as AI writing? And more importantly, will AI detectors flag your text as AI-generated just because you ran it through Grammarly?

What is Grammarly AI?

Grammarly started as a simple grammar checker. It caught typos, suggested better punctuation, and fixed subject-verb agreement. Those features use pattern matching and rule-based logic, not generative AI. They do not create new sentences from scratch.

But Grammarly today is different. Since 2024, Grammarly has added generative AI features that work more like ChatGPT inside your text editor. These include GrammarlyGo for generating whole paragraphs, Compose for drafting new content, Rewrite for rephrasing sentences, and tone suggestions that change how a sentence sounds. These features use large language models to produce original text.

The difference matters. A basic grammar check that fixes "their" to "they're" is not something an AI detector will flag. But a paragraph generated by GrammarlyGo can look as AI-written as anything from ChatGPT.

According to Grammarly's own support documentation, the company says no AI detector today can reliably determine whether AI was used to produce text. That is a fair warning, but it does not mean detectors will not flag Grammarly-edited content anyway.

Does Grammarly trigger AI detectors? We tested 5 tools

To answer this question directly, we ran a 400-word original human-written sample through Grammarly in three modes: basic grammar correction only, Rewrite with tone changes, and GrammarlyGo paragraph generation. Then we tested each version in 5 different AI detectors.

The numbers tell a clear story. Basic grammar fixes are safe and consistently score low across all detectors. Rewrite and tone changes start to push scores higher, especially in Originality.ai and Sapling. GrammarlyGo text gets flagged as heavily AI-written by every detector. But a quick manual edit after using GrammarlyGo brings scores down significantly.

This matches what Originality.ai found in its own testing: copy rewritten by generative AI features inside grammar tools will likely be flagged as AI. The safer choice is to keep Grammarly in proofreading mode and save generative features for tasks where AI disclosure is not a problem.

Which Grammarly features are safe to use?

Not all Grammarly features are created equal when it comes to AI detection. Here is a quick breakdown of what triggers detectors and what does not.

The pattern is simple: the more text Grammarly writes for you, the more likely a detector will flag it. If you only use the red and blue underlines for spelling and grammar, you are almost certainly safe. If you click "Rewrite" on a full paragraph or use GrammarlyGo to draft content from scratch, you should check the result with an AI detector before submitting it.

For a deeper explanation of why detectors flag certain patterns, read Why Does AI Detection Flag My Writing as AI?. It covers the common style patterns that trigger false positives, which is useful for anyone who uses writing assistants.

What does Grammarly itself say?

Grammarly has been careful about this question. When the company launched its own AI detector in 2025, it acknowledged that detection is not reliable enough to be used as a sole judgment tool. Grammarly's blog on how AI detectors work explains that false positives and false negatives are common, and that no detector should be treated as proof.

Grammarly's AI detector scores text based on a proprietary model that looks for patterns typical of LLM output. But the company makes an important point: Grammarly's scores may differ from Turnitin's or GPTZero's scores for the same text. A sentence that looks human to Grammarly's model might look AI-written to another detector.

That is why checking your Grammarly-edited text against more than one AI detector is the only reliable approach. A single score from one tool can give you the wrong sense of safety.

How to use Grammarly without triggering AI detectors

If you want the writing help that Grammarly offers without the risk of being flagged, here is the approach that worked best in our testing.

Start by writing your text yourself, even if it is rough. Use Grammarly for basic spelling and grammar corrections only. Avoid the Rewrite, Compose, and GrammarlyGo features unless you are in a setting where AI disclosure does not matter. If you do use those features, manually edit the result to add your own voice, vary sentence length, and remove any phrases that sound too polished.

Then run the final text through an AI detector like AI Busted to see how it scores. The Best AI Detector for Students guide covers more tools you can use for a second opinion.

The key insight from our test is this: Grammarly is not the problem. The specific AI features you choose to use inside Grammarly are what make the difference. A student who only fixes typos with Grammarly will not get flagged. A writer who uses GrammarlyGo to generate whole paragraphs should expect detectors to notice.

Common Questions

Does Grammarly count as AI for school?

It depends on your school's AI policy. Most schools distinguish between using Grammarly for proofreading and using it for content generation. If your school allows Grammarly for grammar help but bans AI writing tools, the safe choice is to disable Grammarly's generative features when working on assignments.

Can Turnitin detect Grammarly AI writing?

Turnitin can detect text written by Grammarly's generative AI features. In our test, GrammarlyGo text scored 55% AI in Turnitin. Turnitin's system now includes detection for paraphrased AI writing and AI bypasser patterns, which means it is more sensitive to AI-assisted text than before.

Does free Grammarly count as AI?

The free version of Grammarly mainly offers spelling, grammar, and punctuation fixes, which use rule-based logic. These features are very unlikely to trigger AI detectors. However, the free version also includes some tone suggestions and Rewrite features on a limited basis, which could raise scores slightly.

Will Grammarly Premium make my text more detectable?

Grammarly Premium gives you more access to generative AI features like full Rewrite and GrammarlyGo. Using these features more often does increase the chance that a detector will flag your text. But Premium itself is not the trigger. The amount of AI-generated content you accept from the tool is what matters.

How can I check if my Grammarly-edited text is flagged as AI?

The easiest way is to paste your final text into a free AI detector like AI Busted and review the score. If it comes back high, run it through a humanizer or edit it manually to reduce the patterns that detectors look for. Then check again before you submit.