Plagiarism Checker

How the plagiarism check works

Checking every sentence of a text against the whole web is slow and expensive, and most sentences are too ordinary to match anything meaningful. Instead, the checker picks up to six of the most distinctive passages in your text — the ones most likely to be traceable if they were copied — and runs a web search for each. It then compares each passage with the search results and lists only the real matches it finds, labelled as exact or close paraphrase.

Because it is a sample, a clean result means none of the checked passages matched a page the search found. It does not prove that nothing in the text came from anywhere else.

What it does not cover

Be clear about the limits before you rely on a result. The checker searches the public web only.

• It does not search private databases or other students’ submissions.
• It does not search paywalled journals or content behind a login.
• It checks up to 6 passages, not every sentence of the text.
• It cannot find text that was copied and then heavily rewritten.

Using the results fairly

A match is a lead, not a verdict. Open the linked page and look at the overlap: a properly quoted and cited passage, a common definition, or a famous line will legitimately appear elsewhere. Writers can use the check before submitting to catch a quotation they forgot to cite. Teachers can use it as one input alongside their own reading and a conversation with the student.

Example: what a report looks like

Paste an essay and the checker picks up to six of its most distinctive sentences — long, specific ones rather than common phrases — and searches the web for each. The report lists every passage that matched a page, with the page's link, a similarity figure and whether it looks like an exact copy or a close paraphrase, followed by a short summary.

The overall score is the share of the sampled passages that found a match, so one matched passage out of six reads very differently from six out of six. Passages with no match are not proof the text is original — only that those sentences did not turn up in the search.

Tips for a more useful check

Distinctive passages are picked from sentences of at least eight words, so very short answers and bullet lists give the checker little to search for. Paste full paragraphs where you can. Up to 12,000 characters of text, or a PDF, DOCX, DOC or TXT file up to 10 MB, can be checked in one run.

Because each check runs several web searches, it uses three units of your monthly allowance instead of one. If you only need to check one section, paste that section.

• Remove quotations you have already cited, or expect them to match
• Open each matched link and compare the wording yourself
• Check long texts in parts to sample more passages