Interpreting the similarity score

Turnitin does not check for plagiarism in a piece of work. Instead, it checks a user's work against its extensive database. If instances are found where a user's writing is similar to or matches against a source this will be flagged for your review in the match overview.

The database includes billions of web pages: both current and archived content from the Internet, a repository of works students have submitted to Turnitin in the past, and a collection of documents, which comprises thousands of periodicals, journals, and publications.

The color of the similarity score in My Files is based on the amount of matching text in a document.

What do the similarity score colors indicate?

The percentage range is 0% to 100% with the possible similarity indices being:

  Light blue: 0% matching text
  Dark blue: 1-24% matching text
  Yellow: 25-49% matching text
  Orange: 50-74% matching text
  Red: 75-100% matching text

A document's quotes and bibliography can be excluded from the similarity score.

Similarity scoring scenarios

A high similarity score does not always suggest that a piece of writing has been plagiarized, just as a low similarity score does not always indicate that no plagiarism has occurred. Consider the following scenarios:

  1. Submitting a document of considerable size could result in a 0% similarity score with a report that still contains matches. This is because the similarity score has been rounded to 0%, rather than being exactly 0%.
  2. You may have submitted multiple drafts of the same paper to your institution's private repository, meaning your final draft has resulted in a score of 100%. To avoid this issue, we advise that you only submit your final draft to the private repository.
  3. An individual within your institution has managed to acquire a copy of your document. They submit this document to the institution's private repository and receive a similarity score of 25%. You submit your original document a week later to the private repository but receive a 100% similarity score.