Text Similarity Checker
How alike two texts are, letter by letter and by the words they share, with the exact number of edits between them.
Results
What this tool does
"Is this the same text?" has more than one answer. Two paragraphs can be one comma apart or share every word in a different order, and a single percentage would hide the difference. This page gives both: the number of single-character edits needed to turn one into the other, and the share of vocabulary they have in common. Between them they tell you whether you are looking at a typo, an edit, a reshuffle or a different text altogether.
Formula
Levenshtein distance for the letters · for the words, those in both divided by those in either
Variables
| Symbol | Meaning | Unit |
|---|---|---|
text_a | The first text | — |
text_b | The second text | — |
OUT | How alike they are | — |
CS | Letter by letter | % |
WS | By the words they share | % |
ED | Changes needed to get from one to the other | — |
SW | Words in both | — |
OA | Only in the first | — |
OB | Only in the second | — |
SL | The words they share | — |
TR | Text was cut for the comparison | — |
Worked example
- The first textThe quick brown fox jumps over the lazy dog.
- The second textThe quick brown fox leaps over the lazy dog.
- How alike they areNearly the same
- Letter by letter93.2 %
- By the words they share77.8 %
- Changes needed to get from one to the other3
- Words in both7
- Only in the first1
- Only in the second1
- The words they sharebrown dog fox lazy over quick the
- Text was cut for the comparisonNo
Limitations
- The calculation runs entirely in your browser. The values you type are never sent to a server.
Frequently asked questions
Why are there two percentages?
Because they answer different questions. The letter-by-letter figure counts how many single-character changes turn one text into the other, so it notices a typo and is thrown badly by a reordered sentence. The word figure ignores order entirely and asks how much of the vocabulary is shared, so it catches a rewrite that says the same thing in a different arrangement. A pair that scores low on the first and high on the second has been reshuffled, not rewritten.
Why does it cut long texts?
Because the letter-by-letter comparison costs time proportional to the two lengths multiplied together: double both texts and it takes four times as long. Past a few thousand characters a browser would visibly stall, so the character figure is worked out on the first four thousand and the page says so on its own line. The word comparison uses everything you paste, however long.