What does a similarity score mean?

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Updated September 6, 2026 · 6 minute read

A similarity score measures matched text

A similarity score is the proportion of text in a document that matches material in the sources being compared. Those sources can include webpages, publications, and other documents. A score is therefore not the same thing as a plagiarism decision. Context matters: a properly referenced quotation is still a text match.

There is no universal “safe” percentage. Your subject, assignment type, reference style, use of quotations, and your institution's policy can all change what needs attention. A literature review with many correctly cited quotations will naturally look different from a reflective essay.

Why a score can be higher than expected

• Direct quotations or long quoted passages.
• Reference lists, bibliographies, and standard assignment wording.
• Common academic phrases or technical definitions.
• Text reused from your own earlier work where self-citation or permission is needed.
• Paraphrases that remain too close to the source’s sentence structure.

How to read the report well

1. Open the largest matches first and read the surrounding paragraph.
2. Compare the matched wording with the original source.
3. Ask whether it is a quote, a properly cited paraphrase, a standard phrase, or wording that needs revision.
4. Check the assignment and department rules before excluding any type of match.
5. Keep citations accurate; do not remove a citation simply to alter a number.

Improve the writing, not just the percentage

If a paraphrase is too close to a source, return to the original idea, close the source, and explain it again in your own structure and voice. Then add the correct citation. For quotations, use quotation marks and cite the source. If you are uncertain, speak to your supervisor or instructor—especially for dissertations and assessed work.