Why it matters when you are writing
The score is generated by string matching against internet content, published work, and a repository of previously submitted papers. It has no notion of attribution. A literature review that quotes accurately and cites scrupulously can score higher than a thin essay that paraphrases everything loosely, which is the opposite of what a bare percentage suggests.
This is why there is no universal threshold, and why any figure you have heard quoted as a pass mark is invented. Interpretation happens in the report, not in the headline number. Open it and look at what matched: your own reference list matching everyone else’s formatting is meaningless, a common methods phrase is meaningless, a block of continuous unquoted prose matching one source is the thing that matters — and that single block can sit inside a low overall score.
Two facts are worth knowing in advance. Matches against your own earlier submission are common in doctoral work, where a chapter has been submitted before; that needs explaining, not concealing. And instructors can exclude quotations and bibliographies from the calculation, so the score you see in a draft-check may differ from the one your marker sees. Ask what settings apply before drawing conclusions from either.
