Text Similarity Checker

What Is the Text Similarity Checker?

The Text Similarity Checker compares two blocks of text and returns a similarity percentage between 0% and 100%, showing how closely the two pieces match. Paste one text into the first box and another into the second, click Check Similarity, and the result appears instantly. It is used for spotting content duplication, checking whether a rewritten piece is too close to the original, comparing document versions, or getting a quick sense of overlap between two texts without a full plagiarism scan.

A similarity score of 100% means the texts are identical. Anything in the 70% to 90% range usually indicates heavy overlap that is worth investigating, though the right threshold depends a lot on the context and what you are actually checking for.

How to Use This Tool

1. Paste your first piece of text into Textarea 1 above.
2. Paste the second piece of text you want to compare into Textarea 2.
3. Click Check Similarity and the tool calculates a similarity percentage between the two texts and displays the result.
4. Review the percentage to assess the level of overlap. Higher percentages indicate more shared content between the two texts.

When Would You Use This?

Checking whether a rewritten or paraphrased version of an article is distinct enough from the original before publishing, especially if the content was produced by a writer or generator whose output you want to verify.

Comparing two versions of a document, a contract, or a report to see how much has changed between drafts, without reading through every line manually to find the differences.

Doing a quick spot-check for content duplication before submitting academic work, a blog post, or a piece of marketing copy that draws from or rewrites existing material.

Examples

Identical texts

Text 1: The quick brown fox jumps over the lazy dog.
Text 2: The quick brown fox jumps over the lazy dog.
Similarity: 100%

Slightly reworded text

Text 1: The quick brown fox jumps over the lazy dog.
Text 2: A fast brown fox leaps over the sleepy dog.
Similarity: ~55-65% (shares structure and most content words)

Completely different texts

Text 1: The quick brown fox jumps over the lazy dog.
Text 2: She opened the window and looked outside at the rain.
Similarity: ~5-15% (very little shared content)

Heavily overlapping rewrite

Text 1: Content marketing involves creating useful articles to attract and retain customers.
Text 2: Content marketing means producing helpful articles that attract and keep customers.
Similarity: ~75-85% (same structure and most key words)

Frequently Asked Questions

How does the text similarity checker work?

The tool compares the two texts using an algorithm that measures how many words, phrases, or sequences they share relative to their total length. The result is expressed as a percentage from 0% (completely different) to 100% (identical).

What is a good similarity percentage?

It depends on what you are checking. For two pieces that are meant to be original, anything above 30% to 40% might warrant a closer look. For version comparison or editing purposes, a high similarity is expected. There is no single "good" number that applies in every situation.

Is this the same as a plagiarism checker?

Not exactly. A plagiarism checker typically compares your text against a large database of web content and published documents. This tool compares two specific texts directly against each other. It is better suited for comparing a draft to a source, checking two versions of something, or verifying a rewrite.

What algorithm does it use?

Most text similarity tools of this type use sequence-matching algorithms similar to the Ratcliffe/Obershelp method or cosine similarity on word frequency vectors. The exact approach affects how the percentage is calculated and what kinds of similarity it is most sensitive to.

Will two identical texts always show 100%?

Yes. If both text areas contain exactly the same content, the similarity score will be 100%.

Can it compare very long texts?

It can compare reasonably long texts, though very large inputs may slow down the calculation depending on the algorithm used. For extremely long documents, results are typically still usable even if the exact percentage has a slight margin.

Does punctuation and spacing affect the score?

Minor differences in punctuation and spacing may affect the similarity score slightly, depending on whether the tool normalizes text before comparing. Two texts that are identical except for punctuation will likely still score very high.

How do I use this to check if my content was plagiarized?

Paste your text in one box and the suspected source text in the other, then click Check Similarity. A very high score suggests the texts are substantially the same. For a broader web-wide plagiarism check, you would need a dedicated plagiarism detection service instead.