Format
WebP, smaller pictures for the web.
WebP was made by Google for web pages. It compresses photographs like JPG and graphics like PNG, and it keeps transparency.
Safari cannot write WebP itself, so this page includes its own WebP converter and every browser gets the same result.
Facts
The record.
Extension
.webp.
Compression
Lossy or lossless, chosen per file. The lossy mode comes from the VP8 video codec.
Transparency
Kept in both modes, with partial opacity.
Animation
Supported by the format, but Flex Convert does not write it. A GIF converts its first frame only.
Largest picture
16,383 pixels on a side, a limit of the format.
In Flex Convert
Written at Great quality by default. Read in any browser that shows it, which is every current one.
Measured examples
What we measured.
Generated pictures converted to WebP at this site's default quality.
| Test file | Size | Change | Time | Result |
|---|---|---|---|---|
| Transparent logo, 2048 by 2048Chrome | 82 kB → 42 kB | 49 percent smaller | 360 ms | 46.1 dB likeness · 2048 × 2048 · Transparency kept |
| Detailed photo, 12 MPWebKit | 22 MB → 1 MB | 95 percent smaller | 2.2 s | 32.9 dB likeness · 4000 × 3000 |
| Smooth gradients, 12 MPChrome | 423 kB → 64 kB | 85 percent smaller | 660 ms | 49.6 dB likeness · 4000 × 3000 |
Measured on November 7, 2026 in Google Chrome 157, WebKit (Playwright build, not Safari) 26, on Apple M1 Pro. Times run from pressing Convert to the result being ready, with the page already loaded. Likeness is PSNR against the original: higher is closer, and above 40 dB the difference is hard to see. WebKit here is Playwright's build, which is not Safari. Every test file was generated for these measurements, none is anyone else's work, and each is described on the About page.
A smooth gradient went from 423 kB as PNG to 64 kB as WebP. The transparent logo lost 49 percent and kept its transparency. The 12-megapixel detailed photo took 2.2 seconds in WebKit against 1.1 in Chrome, and produced the same size in both.
Good to know
WebP in practice.
Where it helps, and where it gets in the way.
Where WebP came from
Google released it in 2010 to make pages load faster. It took years for every browser to follow, and now all current browsers show it.
Where it is still refused
Some upload forms, older programs and email clients accept only JPG and PNG, and a few social networks recompress or reject WebP. If the destination complains, convert to JPG or PNG instead.
Lossy artefacts
At low quality WebP smooths hard edges, and text in a screenshot can look soft. Use the higher quality settings for text, or keep the PNG.
Choosing
When to pick it, and when not to.
A format is a trade. These are the trades this one makes.
Pick WebP when
the picture goes on a web page and should be small, with or without transparency.
Pick AVIF instead when
you want the smallest file and can wait longer to make it.
Pick JPG or PNG instead when
the destination does not take WebP, or a program you use predates it.