Direct answer
Yes, but only if Grammarly's AI actually wrote the text. Turnitin's AI writing detection scores the prose itself rather than the app you typed it in, so human sentences that were merely grammar-checked are normally fine, while AI-generated sentences can be flagged [1]. The indicator shows an overall percentage of the document that the model predicts was written or modified by an AI tool, and it can even catch AI text later run through a paraphraser [1]. In short: proofreading is low-risk, but Grammarly's generative features (Generate, Rewrite, GrammarlyGO) produce the kind of prose the detector is built to spot.
How Does Turnitin's AI Detector Work on Grammarly-Assisted Text?
Turnitin's detector doesn't look for a "Grammarly signature" — it analyzes the statistical texture of your sentences. The model measures how predictably each word follows the previous one, because AI language models tend to generate highly probable word sequences while human writing is more variable and idiosyncratic [2]. Since detection happens at the text level, the tool you used doesn't matter; only the resulting prose does [2].
That's why "Grammarly-assisted" can mean two very different things to the detector. Passages you wrote yourself and then polished with spelling and grammar suggestions usually keep a human statistical profile, while passages that Grammarly's AI generated for you resemble other LLM output [2]. Turnitin has also expanded its model to flag AI-generated text that was later modified by paraphrasers or bypasser tools, so post-processing a generated draft rarely hides it [1].
The output of all this analysis is simple to read. Turnitin produces an overall AI percentage for the document and links it to a report that highlights the specific segments the model believes were AI-written [1]. Instructors use that percentage and those highlights to decide how to follow up, which is why understanding the report matters before you submit.
Which Grammarly Features Are Likely to Trigger a Turnitin AI Writing Flag?
The dividing line is whether a feature creates new text or only corrects existing text. Grammarly's classic proofreading suggestions don't generate prose, so they don't introduce the AI-generated pattern the detector is trained to recognize [1]. Its generative tools — the AI assistant (GrammarlyGO), Generate, and Rewrite — do create original sentences from a large language model, and those sentences can be flagged.
The problem is that you usually can't test this yourself before submitting. In Turnitin, students cannot self-check a paper without uploading it to an official assignment created by an instructor, unless their institution enables Draft Coach [3]. Even where Draft Coach exists, it runs similarity, citation, and grammar checks rather than the instructor-facing AI indicator [3]. Resubmission limits — about three drafts per 24 hours with longer waits afterward — make repeated trial-and-error checking impractical.
Keep perspective on the flag size as well. The AI percentage reflects the share of qualifying prose the model considers machine-generated, so a few Grammarly-generated sentences inside a largely human essay produce a small score, not a wholesale accusation [1]. A paper built mostly or entirely from generated text, on the other hand, is what the detector is designed to surface.
How Can I Preview My Grammarly-Edited Draft in a Real Turnitin AI Report Before Submitting?
Because the AI indicator lives in an instructor-facing report, the realistic way to preview your risk is to run the draft through a real Turnitin-based check before submission. The AI Writing Report returns an overall percentage and highlights the exact sentences the model predicts were AI-written, so you see precisely where the risk sits [4].
Knowing how the report behaves helps you interpret the result. Turnitin only scores long-form prose of at least 300 words in supported formats, and it displays scores between 1% and 19% as an asterisk (*%) because sub-20% results are considered unreliable [4]. A numeric score of 20% or higher is reportable, while a clean 0% appears as a zero [4].
A pre-submission check converts guesswork into evidence: upload your.docx,.pdf, or.txt, receive the percentage and the highlighted segments, and decide whether to revise before the deadline. That is the same report an instructor would open after you submit, which removes the surprise factor entirely.
Still guessing whether your Grammarly-edited draft will raise a flag? turnitin0 runs your file through the real Turnitin engine and hands back the actual AI writing and similarity reports before you submit — the same reports your instructor sees, delivered in minutes.
※ Turnitin0.com - Actual Turnitin AI Report Cover, Score, Flag And Similarity Summary
FAQ
Does Turnitin flag text that was only grammar-checked by Grammarly?
Generally no. Turnitin's AI writing detection scores the statistical pattern of the prose, and proofreading corrections don't change the underlying human authorship [1]. The indicator only reports text the model believes was generated by an AI writing tool.
Can text generated by Grammarly's AI features be detected by Turnitin?
Yes, when it was actually generated by Grammarly's AI features such as Generate, Rewrite, or GrammarlyGO. Turnitin's model detects content produced by major large language models and tools built on them [1]. The percentage on the report grows with the amount of generated prose in the document.
Can students see their own Turnitin AI score before submitting?
Not through Turnitin itself in most cases. Students cannot self-check a paper without an instructor-created assignment, and Draft Coach focuses on similarity, citations, and grammar rather than the AI indicator [3]. Many students therefore run a pre-submission check through a real Turnitin-based service.
What does an asterisk (*%) mean on a Turnitin AI report?
It means the AI score fell between 1% and 19%, a range Turnitin treats as unreliable and therefore does not display numerically [4]. A clean 0% is shown as zero, while scores of 20% and above are reported as exact percentages [4].
Should I rewrite Grammarly AI text before submitting?
If a pre-submission report shows a numeric AI score, the highlighted segments are what the model sees as machine-generated [4]. Revising those passages in your own words is the most reliable way to reduce the percentage, and checking the draft again afterward confirms the change.