The short answer
The Turnitin similarity score is the percentage of a submission’s words that match text in Turnitin’s database: web pages, publications and papers submitted before. It is not a plagiarism score. Turnitin says plainly that it “does not check for plagiarism in writing”. It highlights matches for a person to review.
There is also no Turnitin-wide “good” score. Turnitin tells students that “there is no fixed number to receive as a score” and that every school, instructor or assignment can set a different acceptable amount. So the useful answer to “is my score good?” is: compare it with the rule your course uses, then look at what the matches are.
What the percentage measures
According to Turnitin’s overview of the Similarity Report, the overall similarity is the number of matching words divided by the total number of words in the document. A submission needs at least 20 words to get a report. Matching text is highlighted, and each highlight points to a source.
What your text is compared against depends on the assignment settings. Turnitin lists:
- current and archived web pages;
- periodicals, journals and other publications;
- papers submitted to Turnitin before, in its repositories.
When the same words appear in several sources, Turnitin shows the source with the most matched words first. So the score is about how much of your text matches, not how many sources you used.
The four match groups
Turnitin’s newer Similarity Report also sorts every match into one of four groups, based on whether it has quotation marks and an in-text citation. Turnitin describes them like this:
| Match group | What it means, per Turnitin |
|---|---|
| Not Cited or Quoted | Matching text with no quotation marks and no citation to its source. |
| Missing Quotations | The text is cited, but the match is so exact that it may also need quotation marks. |
| Missing Citation | The text is written as a quote but has no citation. |
| Cited and Quoted | The text is quoted and cited. Turnitin suggests checking only the formatting. |
These groups are more useful than the headline number. A score made mostly of “Cited and Quoted” matches says something very different from the same score in “Not Cited or Quoted”. Not every institution uses the newer report, so you may not see them.
Turnitin’s color ranges
The report icon is colored by the amount of matching text. Turnitin’s guide to the similarity score for students gives two schemes, depending on the product your institution uses:
| Matching text | Feedback Studio, Originality Check | Similarity, SimCheck |
|---|---|---|
| None (0%) | Blue | Green |
| One word to 24% | Green | Blue (1–24%) |
| 25–49% | Yellow | Yellow |
| 50–74% | Orange | Orange |
| 75–100% | Red | Red |
Turnitin adds that the color scheme “may vary depending on the integration”, so what you see in Canvas, Moodle or another system can differ. The colors are bands of matching text. Turnitin does not describe any color as safe or as a sign of plagiarism, so a red icon tells you to read the report, nothing more.
What is a good similarity score on Turnitin?
Turnitin’s answer is that there isn’t a fixed one. Its student guide asks you to check the syllabus and assignment instructions, read your institution’s policy, or ask your instructor what is expected. Many university help pages publish a range, and they disagree with each other, because each one describes a local practice. A range from another university does not apply to your course.
Turnitin’s guidance on what a score suggests is about balance, not a target:
- A high score could mean that very little of the paper is your own writing. Turnitin’s advice is to balance source material with your own writing and to choose when to paraphrase, summarize or explain in your own words, with each source cited.
- A score of zero may mean the paper uses no source-based evidence, which many assignments require. Turnitin says some similarity is expected, and that a 0% is rare for long assignments that quote at least one source.
Turnitin also says that the kind of writing changes what is normal. Its guide on Turnitin and plagiarism lists research, argumentative and informative writing as genres where similarity is expected, and narrative, creative and reflective writing as genres where it is not. Longer assignments tend to score higher simply because there is more text. For why no number works everywhere, outside Turnitin too, see how much plagiarism is allowed?
Why a high score is not proof of plagiarism
Turnitin answers this directly: a higher overall percentage “is not an automatic indicator of plagiarism” (Turnitin). Its help pages give the usual reasons a score goes up without anyone copying:
- Quotes and references. Quoted text with quotation marks and a reference still shows as a match unless the instructor excludes it.
- Your own earlier submissions. If you submitted drafts of the same paper to the repository, Turnitin says your final draft can score 100% against your own work. Its advice is to submit only your final draft to the repository, and instructors can exclude a student’s previous submissions.
- Your name and other small matches. If your name was on an earlier submission, it can be highlighted. Turnitin suggests that excluding matches under about 10 words usually removes it.
- Templates and common wording. Instructions left in the paper, a cover sheet the whole class uses, and short phrases common in academic writing can all match.
- Source-heavy assignments. Literature reviews and research papers with many citations naturally score higher.
Reusing your own earlier work is a separate question from the score. If you reuse a paper you submitted for another course without permission, that can be self-plagiarism even though you wrote it.
Why a low score is not a clearance
The same Turnitin guidance works the other way. It says a low score “does not guarantee the absence of plagiarism”, and gives contract cheating and “content spinners” as examples of work that is not original but matches little. An idea taken from a source and reworded without a citation is still plagiarism, whatever the number. See is paraphrasing plagiarism?
That is why Turnitin tells instructors to weigh other things: whether the work fits the student’s earlier work and skill level, how well sources are integrated, whether citations follow the required format, and the student’s understanding of academic integrity. Our guide on how to interpret a plagiarism report walks through that kind of reading step by step.
Filters and exclusions that change the score
Instructors can tell Turnitin to leave certain text out of the calculation. These options come from Turnitin’s guide to how exclusion filters refine the Similarity Report. Which ones you can use depends on the version of the report.
| Filter | What it leaves out |
|---|---|
| Exclude bibliography | The reference list. For English papers Turnitin detects it automatically; for other languages it looks for headings such as “References” or “Works cited” and resumes at headings such as “Appendix”. |
| Exclude quoted text | Text inside quotation marks, and indented block quotes in .doc and .docx files. Turnitin lists the quotation mark styles it recognizes. |
| Exclude cited text | In-text citations and the sentences they support. Only in the newer report. |
| Exclude small matches | Matches shorter than a set number of words. The default and minimum is 8 words. Only in the newer report. |
| Exclude small sources | Whole sources whose total match is below a word count or percentage. Classic report only. |
| Exclude a source or match | One source or one highlighted match, for example a student’s own previous draft or permitted reference material. |
Three details from Turnitin’s documentation are worth knowing:
- Students’ exclusions do not count. If you can see your own report, Turnitin says any exclusions you make are temporary and do not change the score your instructor sees. If you think an exclusion should apply, ask your instructor (Turnitin).
- Filters may not move the number much. Turnitin notes that applying them may or may not change the overall percentage, for example when one passage overlaps several sources (Turnitin).
- They do not replace judgment. Turnitin says exclusions refine the process but it is still important to review the remaining matches.
If your score is missing, Turnitin gives two reasons: the instructor turned off student access to the report, or it is still being generated. A resubmitted paper may take up to 24 hours to get a new report, so it does not match the earlier draft.
A worked example
Turnitin’s own scoring scenarios show why the number alone misleads. Two students write the same assignment:
- Student A does not know the topic well and pastes a block of text from a website. Score: 20%.
- Student B gathers several sources and quotes and references them correctly. Score: 22%.
By the number, Student B looks worse. In the report, Student A’s match is one uncited block from one web page, which is plagiarism. Student B’s matches are quoted and cited, which is good practice. Excluding quotes would separate them.
Turnitin gives a second case: a qualitative study with many required quotes and a long bibliography scores 53%, above the institution’s acceptable score. Turnitin’s comment is that this could have been avoided by excluding quotes and the bibliography. The score was high, the work was not the problem.
Checking a draft before you submit
You usually cannot run Turnitin yourself before you submit, and you do not need to. What you can do is make sure every quote has quotation marks, every paraphrase has a citation, and the reference list is complete. The citation generator helps with the references.
The free Plagiarism Checker Plus plagiarism checker shows which passages of a draft match other sources, so you can find a sentence you forgot to quote or cite. It searches different sources from Turnitin, so its percentage will not be the same and is not a prediction of your Turnitin score. Use it to fix credit, not to chase a number.
If your course also uses Turnitin’s AI writing indicator, that is a different number. Turnitin’s AI writing detection FAQ states that the similarity score and the AI writing percentage “are completely independent and do not influence each other”. See does Turnitin detect AI?