Direct answer
A Turnitin similarity report is the document that highlights every passage in your submission that matches text in Turnitin's comparison database, and then expresses the total matched text as a single percentage called the similarity index [1]. That percentage measures overlap with other sources, not plagiarism, and not writing quality — it is a signal for your instructor to investigate, not a verdict [1]. The report also lists each match by source type (internet, publications, student papers) so you can see exactly where the overlap comes from [1].
What does the similarity percentage in a Turnitin report actually mean?
The similarity index is the share of your paper's text that Turnitin matched against its repositories, and it is calculated after any exclusions your instructor has configured — most commonly the bibliography and quoted material [2]. That is why two students with the same score can have completely different reports: one may have 30% from a properly cited literature review, while another has 30% from copied paragraphs with no attribution [2].
Turnitin itself is explicit that there is no "magic number" that separates acceptable from unacceptable work. A percentage is neither good nor bad in isolation; interpretation depends on the discipline, the type of assignment, and the citation conventions of your field [2].
It also helps to know what the number is not. The similarity index is a separate metric from Turnitin's AI writing detection indicator, which is generated by a different model and reported on its own scale with its own confidence threshold [2]. A low similarity score says nothing about whether your prose reads as AI-generated, and a high AI indicator says nothing about whether you copied text.
Does a high similarity score mean I plagiarized?
No. Turnitin states directly that the similarity score is not a plagiarism score — the tool detects matching text and deliberately leaves the judgment to a human reader [3]. Plagiarism is a question of attribution and intent, and software cannot assess either one.
There are many innocent reasons a report can spike. Direct quotations, block quotes, standard methodological phrasing, discipline-specific terminology, reference lists that were not excluded, and even your own earlier draft submitted to a previous assignment can all register as matches [3]. Group projects and shared templates produce the same effect.
This is why instructors read the match overview rather than the headline figure. They check the source breakdown, open individual matches, and ask whether the overlapping text is properly quoted and cited [3]. If it is, a high percentage is usually a formatting or exclusion issue, not an integrity issue — and the fix is a conversation, not a penalty.
How can I see my own Turnitin similarity and AI report before I submit?
Most students cannot run a Turnitin check on demand, because institutional access is controlled by assignment folders that your instructor creates [4]. If your module does not offer a draft or practice submission, you have no built-in way to preview the report before the graded upload.
That gap matters more now that AI detection runs alongside similarity checking. Turnitin's AI writing indicator only displays a numeric percentage when the model is confident; below its threshold it shows an asterisk (*%) instead of a figure, which is a low-confidence signal rather than a clean bill of health [4].
Because of these limits, many students use an independent pre-submission checker to preview both reports on their own draft. That lets you see the similarity index, the source breakdown, and the AI indicator while you can still revise — instead of discovering the result after the deadline has passed [4].
Reading the report is one thing; seeing your own numbers before the deadline is another. turnitin0 gives students a pre-submission preview of the same two reports instructors see — the similarity report and the AI writing report — so you can act on the matches and flags while there is still time to edit.
※ Turnitin0.com - Actual Turnitin AI Report Cover, Score, Flag And Similarity Summary
FAQ
Is a 20% similarity score bad?
Not by itself. Turnitin publishes no threshold that defines acceptable work, and a 20% index can come entirely from correctly quoted and cited sources [2]. What matters is whether the matched passages are attributed.
What is the difference between the similarity index and the AI score?
They come from two separate detection systems. The similarity index measures text overlap with Turnitin's repositories, while the AI writing indicator estimates the likelihood that text was generated by a language model, and it only reports a number above its confidence threshold [2][4].
Why does my report show an asterisk instead of a percentage?
That is Turnitin's low-confidence display. When the AI detection model is not confident enough, it shows *% rather than a specific figure, which should be read as an inconclusive signal rather than a pass [4].
Can I get a Turnitin similarity report without my instructor?
Usually not through Turnitin directly, since institutional checks are tied to instructor-created assignment folders [4]. An independent pre-submission service is the common workaround for students who want to preview both reports on their own draft.
Does a high similarity score go on my academic record?
The score itself is not a finding of misconduct. Instructors review the match overview and source breakdown before drawing conclusions, and properly cited overlap is normally a formatting matter rather than an integrity case [3].