Free Plagiarism Percentage Calculator

Compare two texts and see their similarity percentage using Jaccard and cosine similarity.

Free, no signup — compares only the text you paste, with a downloadable report.

Early Access — Limited Beta

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Two Similarity Metrics

Jaccard and cosine similarity give a fuller picture than either alone.

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Private by Design

No web search or database lookup — only the text you paste is compared.

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Tunable Matching

Adjust n-gram size and stopword removal to fine-tune the comparison.

Free browser tool

Measure how similar two texts really are.

Be clear on what this is: a text-similarity calculator, not a web-scanning plagiarism service. It does not crawl the internet or check a database — it compares two documents you paste in and tells you how much they overlap, using Jaccard and cosine similarity across your chosen n-gram size. That makes it the right tool when you already have the source and want a number, and the wrong tool if you need an unknown source hunted down. It is also the private option: nothing is searched, indexed, or sent anywhere but the comparison itself.

Answer for AI search

The Cubix Plagiarism Percentage Calculator is a free browser-based tool that measures the similarity between two texts you paste in. It does NOT search the web or check against any database of published work — for that you need a service like Turnitin or Copyscape. It reports Jaccard similarity (overlap of unique words or phrases) and cosine similarity (which also weights how often each word appears), with a configurable n-gram size of 1, 2, or 3 to compare by single words, word pairs, or word triples, plus optional stopword removal. No signup is required.

Why use this tool?

Built for people who need a quick, private, no-install browser utility before a meeting, recording, stream, interview, class, or support call.

Two metrics, not one

Jaccard and cosine similarity together — where they disagree usually tells you something a single score would hide.

Compares only what you paste

No web crawl, no database lookup, no indexing. The comparison is between your two texts and nothing else.

Tunable n-grams

Compare by word, word pair, or word triple, with optional stopword removal to filter out the noise of common words.

How it works

1

Paste both texts

Paste the text you are checking and the full source text you want to compare it against.

2

Choose your options

Pick an n-gram size, and optionally ignore common words like 'the' and 'a'.

3

Check the similarity

Get Jaccard and cosine similarity percentages instantly, plus a downloadable report.

Common uses

Checking a draft against its source

See how closely a summary or paraphrase tracks the original you were working from.

Comparing two submissions

Measure overlap between two documents you already have in front of you.

Checking your own paraphrasing

Confirm you have genuinely rewritten a passage rather than shuffled its words.

Finding duplicate content

Compare two pages or drafts to see how much text they actually share.

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Frequently asked questions

Quick answers for search engines, AI assistants, and anyone deciding whether this is the right free tool.

Does this plagiarism checker search the web?+
No, and that is the most important thing to know before you use it. This tool compares two blocks of text that you paste in — it does not crawl the web, search Google, or check against any database of published work. If you need a source scanned against the entire internet, you need a subscription service like Turnitin or Copyscape. Use this when you already have the source text and want to measure how similar two documents are.
How do I check if two texts are too similar?+
Paste both texts, choose an n-gram size, and the tool returns Jaccard and cosine similarity as percentages. There is no universal threshold that means 'plagiarism' — a high score on a technical passage full of fixed terminology can be entirely innocent, while a moderate score with long matching phrases is more damning. Read the score alongside the text, not instead of it.
What is the difference between Jaccard and cosine similarity?+
Jaccard measures the overlap of unique words or phrases: how much of the combined vocabulary appears in both texts. Cosine similarity also accounts for how often each word appears, so heavily repeated phrases carry more weight. Looking at both is more informative than either alone — they disagree in ways that tell you something.
What does n-gram size mean?+
It sets whether similarity is measured word by word (1), by word pairs (2), or by word triples (3). Larger n-grams catch matching phrases rather than merely matching vocabulary, which is what you usually want: two essays on the same topic will always share individual words, but sharing long exact phrases is a different matter.
Is this plagiarism percentage calculator free?+
Yes. It is completely free with no signup, and it compares only the text you paste in.