WebP Format Explained — Lossy, Lossless, Transparency and Animation in One
WebP explained: Google's 2010 format, VP8 lossy and lossless modes, RFC 9649 (2024), size vs. JPG and PNG, and 2026 browser and Android support.
WebP is a format Google released in 2010 to reduce the size of web images. Inside a RIFF container, it holds a lossy mode based on the VP8 video codec and a separately designed lossless mode, and both modes support transparency and animation. In November 2024, 14 years after its release, the IETF formally registered the specification and the media type image/webp as RFC 9649.
File size — Google's published figures
According to Google's developer documentation, lossy WebP is 25–34% smaller than JPG at the same SSIM quality index, and lossless WebP is 26% smaller than PNG. When transparency is needed, lossy WebP can produce files about 3 times smaller than PNG. These are Google's test results, so actual savings depend on the image and encoder settings.
Browser and OS support (as of 2026-09-23)
According to Can I use data, about 96% of browser users worldwide can display WebP.
| Browser | Full support since |
|---|---|
| Chrome | 32 |
| Edge | 18 |
| Firefox | 65 |
| Safari (macOS) | 14 (Big Sur or later), no OS restriction from 16 |
| Safari (iOS) | 14 |
The Photos app in Windows 10/11 and Preview on macOS can open WebP, but older image editors, some document programs and government upload forms often don't accept it.
File structure
A WebP file starts with a RIFF header, the file size and a WEBP marker. Chunks follow depending on the image type.
VP8— lossy compressed image dataVP8L— lossless compressed image dataVP8X— indicates extended features (transparency, animation, metadata)ALPH— transparency channel for lossy imagesANIM·ANMF— animation settings and individual framesICCP·EXIF·XMP— color profile and metadata
Android support
According to the Android developer documentation, basic WebP decoding and encoding are supported from Android 4.0, transparency and lossless decoding from 4.2.1, and lossless encoding from Android 10.
Strengths and limitations
- One format handles photos (lossy), graphics (lossless), transparent backgrounds and animated images.
- Lossy mode always stores chroma at half resolution (4:2:0), so thin colored lines such as red text can bleed. Lossless mode is better for such images.
- The maximum size is 16,383 pixels per side, so very large panoramas won't fit.
- It only supports 8 bits, so AVIF is better suited to HDR photos.
Main uses
Website and blog images, web graphics that need transparent backgrounds, and short animations replacing GIF.
When to switch to WebP and when not to
| Situation | Recommendation |
|---|---|
| Photos on blogs and product pages | WebP recommended — less data transferred |
| Web graphics with transparent backgrounds | WebP recommended — smaller than PNG |
| Submissions to government offices or schools, sending to a print shop | Keep JPG/PNG |
| Photos sent by messenger or email | Keep JPG — compatible with the recipient's software |
| Masters you'll keep editing | Keep PNG or the original format |
Converting to other formats
- WebP → JPG: The most common conversion, for compatibility with documents and upload forms. Transparent areas are filled with the background color (WebP to JPG).
- Animated WebP → still image: Most conversion tools save only the first frame.
- JPG → WebP: Loss is added on top of the original JPG's loss, so a quality of around 75–85 is a safe choice (JPG to WebP).