Direct answer
Grammarly does include an AI detector that flags text likely produced by an AI generator, but it is a writing assistant's signal, not an academic-integrity verdict, and it will not match the Turnitin AI score your institution sees. Grammarly itself describes its detector as a probabilistic indicator rather than proof, and notes that no detector is fully accurate [1]. If your grade depends on a submission, the score that matters is the one produced by the system your school actually runs — usually Turnitin — so treat Grammarly as a first-pass sanity check and verify the real number separately [3].
Does Grammarly Detect AI-Generated Text, And How Accurate Is It?
Yes, Grammarly surfaces an AI-detection signal, but its accuracy is conditional rather than fixed. Grammarly frames the feature as a probabilistic indicator: it estimates the likelihood that a passage was generated by AI and expects readers to weigh that estimate against context, drafting history, and the writer's own knowledge of how the text was produced [1]. That framing matters because a "likely AI" label is an inference about statistical patterns, not evidence about authorship.
Accuracy also shifts with the text itself. Detector performance changes with document length, genre, and how heavily the draft has been edited, and false positives show up most often on formulaic or heavily revised human prose — literature reviews, methods sections, and text that has been smoothed repeatedly by a grammar tool [2]. Short passages give the model less signal to work with, so a two-paragraph flag is far weaker than a flag across a full essay [1].
The practical consequence is that a clean Grammarly result is not a guarantee, and a flagged Grammarly result is not a confession. Grammarly's own guidance points users toward conversation and context rather than punitive conclusions [2]. For students, that means the tool is useful for spotting passages that read mechanically, but it cannot tell you what a marker's report will say.
Why Does Grammarly Show A Low AI Score While Turnitin Flags The Same Draft?
The two tools are answering slightly different questions with different models, so disagreement is expected rather than anomalous. Turnitin's AI writing indicator works at the document level: it segments the submission and reports the percentage of qualifying prose that its model classifies as AI-generated, and it deliberately excludes elements such as references and quoted material from that calculation [3]. A Grammarly score computed over a differently segmented document, with different thresholds, can land in a very different place.
Thresholds and display rules widen the gap further. Turnitin shows an asterisk (*%) instead of an exact figure when the AI score falls below its 20% confidence threshold, which means a low-confidence signal is being displayed rather than a precise percentage [3]. A student comparing that asterisk to a Grammarly percentage is comparing a confidence-gated band to a raw estimate — the numbers are not on the same scale, and neither one is a like-for-like substitute for the other.
There is also an editing effect worth naming. Running a draft through a grammar assistant repeatedly tends to regularise sentence rhythm and vocabulary, which is exactly the kind of smoothing that detector models associate with generated text [2]. So a draft can be substantially human-written and still drift toward the flagged pattern after several polishing passes — a scenario Turnitin's prose-only, segment-based reporting is designed to describe more conservatively than a per-sentence checker [3].
How Can You Check Your Draft's Real Turnitin AI Score Before You Submit?
The reliable move is to obtain the same class of report your institution generates, before the deadline rather than after it. Students generally cannot trigger an institutional Turnitin check on their own account, and preview routes that sit outside the learning management system exist precisely because that gap is common [4]. What you want is a report showing the AI-writing percentage plus the similarity summary, so you can see both signals at once instead of guessing from a single number.
When you preview, match the conditions of the real submission. Upload the same file type and word count you plan to submit, and run the check without adding the draft to a student paper database, so the preview does not create a similarity match against your own later submission [4]. Read the AI result the way Turnitin reports it — as the share of qualifying prose flagged, with low-confidence results shown as *% rather than a precise figure [3].
Then act on what the report shows. If the flagged passages are the ones you drafted with an AI generator and then lightly edited, revise them at the sentence level: restore your own examples, vary sentence length, and cut the connective phrasing that reads as templated [2]. Re-check after revision rather than assuming a rewrite worked, since detector output on edited text is not predictable from intuition alone [1]. A second preview is far cheaper than an appeal.
Reading a writing assistant's estimate is a reasonable first step, but it leaves you exactly where you started: unsure what the marker's report will say. turnitin0 closes that gap by producing the actual Turnitin AI detection report and similarity report on your own draft, delivered in under 15 minutes in 98% of cases, with the file checked non-repository so your work is never added to the student paper database. You see the same report view your professor sees — score, flagged passages, and match highlights — while there is still time to revise.
※ Turnitin0.com - Actual Turnitin AI Report Cover, Score, Flag And Similarity Summary
FAQ
Is Grammarly's AI checker the same as Turnitin's?
No. They are separate models with separate thresholds and reporting rules, and Turnitin reports the share of qualifying prose flagged while excluding references and quotes [3]. Grammarly presents its result as a probabilistic indicator that should be read alongside context [1].
Can Grammarly's AI detector give a false positive?
Yes. Detector accuracy varies with length, genre, and editing intensity, and heavily revised or formulaic human writing is where false positives concentrate [2]. A single flagged paragraph is weak evidence on its own.
If Grammarly says my text is human, am I safe?
Not necessarily. A clean writing-assistant result does not predict an institutional score, because the two systems segment and threshold text differently [3]. The only way to know your Turnitin AI percentage is to obtain a Turnitin report on the same draft [4].
Does running my essay through Grammarly make it look AI-generated?
Repeated polishing can regularise rhythm and vocabulary, which is the pattern detectors associate with generated text [2]. If you have made multiple passes, verify the result rather than assuming the edits were neutral [1].
Will a pre-submission check add my paper to Turnitin's database?
A non-repository check does not add your file to the student paper database, and reports are not shared with third-party databases [4]. That keeps a preview from creating a similarity match against your own final submission.