Turnitin Similarity Score: What It Means and What Is a Good Percentage

The Turnitin similarity score is the percentage of the words in a student’s submission that match text in Turnitin’s database. It is a measure of overlap, not a verdict: Turnitin states that it does not check for plagiarism, and a person has to read the matches to decide what they mean. This guide covers how the score is worked out, what each color means, why quotes and references raise it, and why no single percentage counts as “good” everywhere. It is part of our academic integrity guides.

What the Turnitin similarity score measures

When a Turnitin similarity report is ready, the similarity score appears as a percentage next to your submission. Turnitin’s Understanding the similarity score guide describes it as the share of a submission that matches other sources. Put simply, it is the number of matched words out of the total words in the paper. If 300 words of a 2,000-word paper match, the score is 15%.

The database it compares against includes current and archived web pages, journals and other publications, and papers that other students have submitted. Anything in your text that is similar to one of those is highlighted. The similarity report then lists the origin of each highlight so a reader can judge whether it is acceptable.

That is why the Turnitin similarity score is a starting point for a review by students and instructors. A highlighted sentence might be a properly cited passage, a common phrase, or text copied without credit. The percentage cannot tell these apart. For what actually counts as plagiarism, see what is plagiarism.

Turnitin colors meaning: what the score badges signify

The report icon is colored by score. For classic assignments in Feedback Studio and Originality Check, Turnitin’s student guide lists these ranges:

Color	Matching text	What it tells you
Blue	No matching text	Nothing in the paper matched a source.
Green	One word to 24%	Some matches, which is normal for a paper with quotes and references.
Yellow	25-49%	A large share matches. Check which sources and why.
Orange	50-74%	Most of the paper overlaps. A reader will want to open the report.
Red	75-100%	Almost all of the text matches. Often a sign of a repository or quotation issue, or of copied text.

The third column is our reading of the ranges, not Turnitin’s. Turnitin only gives the percentages.

Why quotes and references raise your score

Correctly cited text still counts as matching text. Turnitin says this plainly in its guide: quotation marks and a citation do not stop the words from counting. Your bibliography is also flagged, because other papers list the same works.

Turnitin’s own example makes the point. A student who pasted a chunk from a website scored 20%. Another student who quoted and referenced several sources correctly scored 22%. Both reports show matching text, and only the context shows which paper is the problem. In a second example, a qualitative study with many quotations and a long bibliography scored 53%, above the school’s limit.

For how to quote and paraphrase so that your own writing carries the paper, see how to avoid plagiarism.

Excluding quotes and the bibliography from the similarity report

Quotations and the reference list are the two most common reasons a well-written paper scores high, and Turnitin lets the similarity report leave them out. The setting belongs to the instructor, so you cannot switch it on yourself, but you can ask whether it is on. Turnitin’s 53% qualitative study is the clearest case: the limit was exceeded because quotations and the bibliography were counted, and the guide says excluding them would have avoided the problem.

Two practical points follow. First, never delete a citation or a reference entry to bring the similarity score down, because the paper then fails the real test, which is honest sourcing. Second, ask your instructor three things: are quotations excluded, is the bibliography excluded, and is there a minimum word count for matching text? Short matches such as a name or a common phrase can be excluded by length.

What is a good Turnitin percentage?

There is no universal good Turnitin similarity score. Turnitin’s student guide says there is “no fixed number to receive as a score” and that every school, instructor or assignment can have a different amount of matching text that is considered acceptable. Websites that publish a safe range, such as under 15% or 20%, are giving rules of thumb for students. They are not Turnitin’s thresholds.

The same applies to the question of how much plagiarism is acceptable. Because the score is not a plagiarism measure, no percentage is “acceptable plagiarism.” What matters is whether the matched text is quoted, referenced or common wording, or whether it is someone else’s work presented as yours.

To find your own target, do this before you submit:

• Check the syllabus and assignment instructions for a similarity expectation.
• Read your institution’s policy on acceptable similarity.
• Ask your instructor which sources, quotes and bibliography are excluded.

A high score can mean very little of the paper is your own writing, so balance source material with your own explanation. A very low score is not automatically the goal either. Turnitin notes that zero similarity may mean you included no source-based evidence, which many assignments require.

Cases where the score misleads

These are the situations Turnitin’s guides describe where a number does not mean what it appears to.

Situation	What happens	What to do
Earlier drafts in the repository	Several drafts were saved to the institution’s private repository, so the final draft matches your own earlier drafts and scores up to 100%.	Submit only the final draft to the repository, as Turnitin advises. An instructor can also exclude your earlier submissions.
0% with matches in the report	On a large document the score is rounded, so a paper can show 0% and still contain matches.	Open the report instead of relying on the number.
Someone submitted your paper first	A classmate who gets a copy and submits it scores 25%. You submit the original later and score 100%.	Expect the after-deadline check. Turnitin runs a final comparison across all submissions, which exposes the copy.
Your name highlighted	If a paper with your name was submitted before, your name can show as a match.	Instructors can exclude small matches, and Turnitin says excluding 10 words should safely remove a name.
Resubmitting a draft	An overwritten or resubmitted paper may not get a new report for 24 hours.	Allow a full day before a deadline, and do not keep resubmitting.

Resubmitting a draft and the 24-hour report delay

If you overwrite or resubmit a paper, Turnitin says the new similarity report may not appear for a full 24 hours. The delay is automatic, and it exists so that your resubmission is not matched against your own previous draft. It means that a student who uploads a fix an hour before the deadline may still see the old number.

The related risk is the repository. If each draft is saved to your institution’s private repository, the final draft can match the earlier ones and reach 100%. Turnitin’s advice is to submit only the final draft to the repository. If you have already done so, tell your instructor, who can exclude your previous submissions from the report.

What to do with your Turnitin similarity report

Open the similarity report rather than reacting to the percentage. Work through the highlighted passages and ask three questions for each: is it a quotation with a reference, is it a common phrase or title, or is it wording I took from a source without credit? Fix the third kind by rewriting in your own words and citing the origin, then resubmit if your instructor allows it.

If your score is not visible, Turnitin lists two reasons: your instructor turned off student access to the report, or the report is still being generated.

Frequently asked questions