WebP usually beats both JPEG and PNG, but not always — which is exactly why the tool measures instead of assuming.
—
80
Resize
50
Encoder detail
6
fastzopfli
256
28
0 lossless51 tiny
The largest saving available.
50
Speed, audio and advanced
8
0 smallest13 fastest
128
96
Advanced
8
Nearly all of the saving comes from the images inside.
150
75
Advanced
50
aggressivegentle
Advanced
14
coarsefine
0 merges only exactly equal vertices. A small value also closes hairline cracks left by CAD exporters.
Geometry only — texture coordinates,
materials and vertex colours are not carried through. Decimating a
UV-mapped mesh correctly is a much harder problem, and mangling your
UVs quietly would be worse than leaving them alone.
12
6
Advanced
ZIP and 7z. 7z encrypts the file list too.
What actually shrinks WebP files
Encoding uses the browser's own libwebp build, so it runs at native speed on your machine and nothing is uploaded.
On a noisy photograph JPEG sometimes still wins. Auto mode encodes both and keeps the smaller file.
WebP keeps transparency, so it is usually the right replacement for a large PNG that needs an alpha channel.