Measure how hard an image has been compressed, and whether it is worth optimising.
JPEG, PNG, WebP, GIF, BMP or AVIF, up to 40 MB
Processed on your device — nothing is uploaded
A web photo
Check whether it is worth optimising
hero.jpgAn over-compressed image
Low bits per pixel, visible artefacts
thumb.jpgA PNG photograph
Often the wrong format for the content
photo.pngThe format is identified from the file signature, not the file name.
Bits per pixel, dimensions, real format, transparency use and estimated savings.
The analysis links to the right tool for whatever it recommends.
Bits per pixel normalises for size, so it tells you something a raw file size cannot: whether the compression is aggressive relative to the amount of image being stored.
A photograph stored as PNG, or a transparent image saved without any transparent pixels, both show up here — and both usually mean a much smaller file is available.
The potential saving is calculated by actually re-encoding the image at a reference quality, not guessed from a table.
Work out whether an image is over-compressed, under-compressed, or larger than it needs to be. The main measure is bits per pixel — file size divided by pixel count — which is the standard way of describing compression pressure independently of dimensions, so a 4000-pixel-wide photo and a thumbnail can be compared on equal terms. Alongside it the tool reports the real format detected from the file signature rather than the extension, the dimensions, whether transparency is actually used, and an estimate of what re-encoding could save. Everything is measured from your file locally.
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