Understanding the Similarity Score
The Similarity Report
Turnitin does not check for plagiarism. What we actually do is compare your submissions against our database and highlight wherever your writing is similar to one of our sources. Our database includes billions of web pages: both current and archived content from the internet, a repository of works other students have submitted to Turnitin in the past, and a collection of documents, which comprises thousands of periodicals, journals, and publications.
The Similarity Report provides a summary of details, including the sources matched to your submission, to use as a tool to determine if the matches are acceptable. When a Similarity Report is available for viewing, a similarity score percentage is made available.
The Similarity Score
The similarity score is the percentage of matched text your submission contains. We calculate this by dividing the total words in a submission by the amount of words matched to outside sources.
INFO: It is likely your submission will match against some of our database. If you've used quotes and references correctly, that will still be highlighted as a match.
What do the similarity score colors indicate?
The color of the similarity score in My Files is based on the amount of matching text in a document.
The percentage range is 0% to 100% with the possible similarity groupings being:
- Green: 0% matching text
- Blue: 1-24% matching text
- Yellow: 25-49% matching text
- Orange: 50-74% matching text
- Red: 75-100% matching text
Similarity score 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:
- 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%.
- 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.
- 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.
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