Compare two images and calculate their visual similarity percentage.
Upload two images and the tool reports how visually alike they are as a percentage. The comparison runs entirely in your browser - the images never leave your device, which matters for screenshots or documents you would not want to upload anywhere. Identical content scores at the top of the range, and any change to the picture - recompression, resizing, a crop, a color shift - pulls the score down by some amount. The surprise for most users: a re-encoded copy of the same photo rarely scores 100%, and two photos of the same scene can score high even though neither was derived from the other.
The score measures how closely the two images' visible content matches when compared as uploaded. Pixel-identical images produce the top score; anything that changes what the picture shows - encoding, compression, resizing, cropping, color changes - lowers it. Only what the images look like counts: file size, format, and metadata are not part of the comparison.
Each kind of change costs a different amount. Recompression that preserves detail costs little; heavy compression, cropping, or rotation costs a lot, because large parts of the image no longer align with the other version. Images of different dimensions cannot be compared pixel for pixel, so the result depends on how they are resized or aligned to line up, and that adjustment can cost points on its own.
No. A top score means the two images look the same; the files themselves can still differ - a different format, an extra compression pass, or different metadata. For byte-level equality, compare file checksums instead. And any visible difference, however small, tends to hold the score just below the top of the range.
Resizing changes the pixel grid. To compare images of different sizes, one must be rescaled to match the other, and resampling always alters some pixels - fine detail gets sharpened, softened, or shifted by half a pixel. A resized copy therefore rarely reaches the top of the range even when it looks identical to the eye.
The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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