Direct answer
Turnitin's essay grader is the combination of similarity checking and AI writing detection that instructors see the moment they open a submitted paper. Feedback Studio, the grading environment behind it, matches essay text against an enormous database of academic content and evaluates whether passages appear to have been written by an AI tool [1]. The result is a two-report verdict — a similarity score and an AI writing percentage — alongside the comment and rubric tools instructors use to grade [1].
How Does the Turnitin Essay Grader Work?
When an instructor opens your essay, Turnitin's AI writing detection evaluates the document and produces an overall percentage reflecting how much of the prose is likely AI-generated [2]. The report also highlights the specific sentences and paragraphs where AI-suspected writing appears, so the verdict is visible at both the document and sentence level [2]. This AI writing report sits side by side with the similarity report in the instructor's grading view.
The similarity layer is the older, better-known part of the grader: it compares your essay against academic papers, websites, and previously submitted student work, then highlights matched passages [1]. Together, the two reports give instructors a fast snapshot of whether an essay is original and human-written. Neither score is an automated grade — they are signals the instructor weighs alongside the quality of the writing itself.
Turnitin explicitly designs the AI writing indicator to support human judgment, not replace it [2]. The report is one data point among many, and instructors are advised to interpret it carefully before drawing conclusions about a student's work [2]. That is why the same essay can receive very different feedback from different markers.
What Do the Scores on a Turnitin Essay Report Mean?
The AI writing report displays an overall percentage from 0% to 100%, estimating how much of the essay's prose was produced by an AI tool [3]. Any score below 20% is shown as an asterisk bucket (*%) rather than a single-digit number, and 0% is the only explicit low numeric result students typically see [3]. Scores in the 80–100% range indicate the document was highly likely written entirely by AI, while mid-range scores suggest a mix of human and AI text.
The similarity score is a separate number that measures how much of the essay matches existing sources — it is not the same thing as an AI score [1]. A low similarity score does not prove an essay is human-written, and a high one does not prove AI involvement. Students often confuse the two because both appear as percentages on the report.
Turnitin is transparent that AI writing detection is not infallible, and its guidance emphasizes caution when interpreting results [3]. The detection indicator is most reliable on longer documents, and false positives remain possible on short or heavily edited text [3]. For that reason, the score is framed as a conversation starter, not a definitive accusation.
Can You Check Your Essay With Turnitin Before You Submit It?
Turnitin's official guidance encourages students and educators to talk openly about AI writing detection before and after submission [4]. The company frames the indicator as a starting point for discussion rather than a punishment, and it recommends transparent communication about how the reports work [4]. When students understand what the grader checks, they can review their own drafts with the same lens.
That matters because, in most institutional setups, the AI writing report is only visible to instructors — students rarely see their own AI percentage in the submission inbox [2]. The similarity report may be shared at the instructor's discretion, but the full verdict usually appears only after you submit. Knowing what the report will show before it lands in front of your instructor is the entire advantage of previewing it.
The practical workaround is to run your draft through a service that generates genuine Turnitin similarity and AI writing reports before you submit [1]. This gives you the same two-report verdict your instructor will see — scores, flags, and highlighted matches — while you still have time to revise [1]. It turns the grader from an unknown into a checklist you can act on.
The smartest time to understand your Turnitin scores is before your instructor does. turnitin0 gives you the exact reports your professor will see — real Turnitin AI writing and similarity reports generated on your own draft — so flagged sentences can be fixed before they cost you marks.
※ Turnitin0.com - Actual Turnitin AI Report Cover, Score, Flag And Similarity Summary
FAQ
Is the Turnitin AI writing report visible to students?
Not in most setups. The AI writing report is instructor-facing, and students usually do not see their own AI percentage in the submission inbox [2]. Similarity reports may be shared at the instructor's discretion [1].
What does an asterisk (*) mean on a Turnitin AI score?
Any AI writing score below 20% is displayed as *% instead of a single-digit number [3]. The only explicit low numeric result students typically encounter is 0%.
How reliable is Turnitin's AI writing detection?
Turnitin states that detection is not infallible and advises interpreting the indicator with care, especially on shorter documents [3]. It is designed to support instructor judgment rather than act as a standalone verdict [2].
What is the difference between the similarity score and the AI writing score?
The similarity score shows how much of the essay matches existing sources, while the AI writing score estimates how much of the prose was written by an AI tool [1][2]. They are separate numbers that answer different questions [3].
Can I preview my Turnitin report before submitting my essay?
Yes — you can generate real Turnitin AI and similarity reports on your draft before submission through services such as turnitin0 [1]. Previewing beforehand lets you address flags and highlights while you still have time to revise [4].