You have submitted a draft, the report has come back, and there is a coloured percentage at the top of it. Before you panic, the important thing to understand is that the number on its own means almost nothing.
This guide explains what a Turnitin similarity score actually measures, what counts as normal, and when a percentage genuinely is a problem.
What the score actually measures
Turnitin compares your text against its database of student papers, published work and web pages, then reports how much of your submission matches something it has seen before.
That is all it does. It is a text-matching tool, not a plagiarism detector, and Turnitin itself is careful to say so. The software cannot tell the difference between a properly quoted and cited passage and a stolen one, because both are matches. Deciding which is which is a human judgement your marker makes by reading the report.
This is why a high percentage is not automatically an accusation, and why a low percentage is not automatically a clean bill of health.
What counts as a normal score
Most universities do not publish a threshold, precisely because the number needs interpreting. That said, the ranges markers tend to work with look roughly like this.
Under 15 per cent
Typical and rarely examined further. At this level the matches are usually references, common phrases and correctly quoted material.
Between 15 and 25 per cent
Common in dissertations and in any work with a long reference list or extensive quotation. Usually fine, though a marker may glance at where the matches fall.
Between 25 and 40 per cent
Worth investigating yourself before submission. This often means over-quoting or paraphrasing too closely rather than anything deliberate, but it will attract attention.
Above 40 per cent
Likely to be reviewed. Occasionally there is an innocent explanation, such as a methods section that necessarily repeats standard protocol wording, or a template your department supplied. More often it indicates a real problem with how sources have been used.
The exception worth knowing: some departments set a hard threshold in the handbook, and where they do, that number applies regardless of the guidance above.
Where the matches fall matters more than the total
This is the part students consistently miss.
A 30 per cent score spread thinly across dozens of one-line matches to reference entries and standard terminology is not a concern. A 12 per cent score made up of one unbroken passage lifted from a single source is a serious one, and it will be treated as such even though the number is lower.
So open the report itself rather than reading the headline figure. Look at the source breakdown. One large match from one source is the pattern that causes trouble.
What inflates a score harmlessly
Several things push the percentage up without indicating any wrongdoing:
- The reference list, which matches everyone else’s citations of the same works. Most institutions can exclude the bibliography from the count, and many do.
- Direct quotations, correctly marked and cited. These can also usually be excluded.
- Standard terminology in technical and legal subjects, where there is only one correct way to name something.
- Your own earlier draft, if a previous version was submitted to Turnitin. This produces alarming scores and is easily resolved by telling your tutor.
- Common phrasing such as “the results of this study suggest that”, which appears in thousands of papers.
If your score looks high, check whether quotes and bibliography were excluded before you assume the worst.
What a low score does not prove
A score of two per cent is not evidence that your work is original. It is evidence that your wording does not match anything in the database.
Turnitin will not catch an idea taken without attribution and rewritten in your own words. That is still plagiarism, and it is caught by markers who know the field rather than by software. Nor will a similarity report tell your marker whether you wrote the text yourself, which is a separate question handled by different tools and discussed in our guide on AI detection at university.
How to bring a high score down legitimately
The right fix depends on why it is high.
If you are over-quoting, paraphrase instead and keep quotations for wording that genuinely matters. A dissertation should rarely be more than five per cent direct quotation.
If your paraphrasing is too close, the problem is method rather than vocabulary. Swapping individual words for synonyms produces text that still matches and still counts as plagiarism. Read the passage, close it, and write the point from memory in your own structure. There is a fuller explanation in our guide on how to paraphrase without plagiarising.
If one source dominates, you are relying on it too heavily. Bring in other work and compare, which improves your mark as well as your score.
What not to do: never use a spinner or article rewriter to defeat the match. The output reads badly, markers recognise it instantly, and at many institutions attempting to evade detection is itself a disciplinary offence, separate from plagiarism.
Common questions
Does Turnitin store my work?
Usually yes, in the student paper repository, which is why resubmitting a draft can match your own earlier version. Some submission points are configured not to store, and your tutor can tell you which applies.
Can I check my work before the real submission?
Many universities provide a draft submission point exactly for this. Ask your module leader. Avoid third-party checking sites, since some add your paper to their own database, which can then flag your real submission.
Is a zero per cent score suspicious?
Not in itself, though it is unusual in work with a reference list. It sometimes indicates that the file did not process correctly, so it is worth opening the report to confirm the text was actually read.
Does Turnitin detect paraphrasing?
It detects close paraphrasing where sentence structure survives. It does not detect genuine restatement in your own words and structure, which is the standard you should be writing to anyway.
If your score has come back high
Read the report before doing anything else, and look at the pattern of matches rather than the total. Most high scores turn out to be quotation and referencing rather than misconduct, and they are fixable in an afternoon.
Our plagiarism and AI removal service rewrites over-matched passages properly, with sources correctly attributed rather than disguised, and our proofreading and editing service covers the referencing pass that prevents most of these problems in the first place.