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WebP: the web's everyday image format

WebP is an image format made for the web. It does lossy compression like JPEG and lossless compression like PNG, supports transparency and animation, and usually produces smaller files than either. Every current browser supports it — but some apps, upload forms and print services still don't, which is why a downloaded .webp sometimes won't open where you need it.

WebP at a glance

File extensions
.webp
MIME type
image/webp
Compression
Lossy (based on the VP8 video codec) or lossless — two separate modes in one format.
Transparency
Yes, in both lossy and lossless mode, with smooth alpha.
Animation
Yes. Animated WebP is a much smaller replacement for GIF.
Colour
8 bits per channel. Lossy mode stores colour at half resolution, like most JPEGs.
Browser support
Every current browser. Safari was the last major one to add it, in 2020.
In ImageDoctor
Opens, compresses, resizes, crops and converts WebP. WebP output uses your browser's encoder, so it is offered only where the browser can write it. Animated WebP is reduced to its first frame.

Why you keep getting .webp files

Websites increasingly serve WebP because it makes pages load faster. When you right-click and save an image, your browser saves what the site sent — so the "photo" you downloaded is a .webp, even if the page never mentioned it. The image is fine; the question is only whether the place you are taking it next can read it.

Current versions of Windows Photos and macOS Preview open WebP, as does every browser (drag the file into a tab). If a form, an older program or a print service rejects it, convert it: WebP to JPG for photos, WebP to PNG if it has a transparent background.

Two formats in one

WebP has two entirely different compression modes that share a file extension:

  • Lossy WebP works like a modern JPEG: at matched visual quality it is typically 25–34% smaller, in Google's own study. Like JPEG, it stores colour at half resolution, so very fine coloured detail — thin red text, for instance — can soften.
  • Lossless WebP keeps every pixel, like PNG, and is usually smaller than the equivalent PNG — about 26% smaller on average in the same study.

Both support an alpha channel, which is the practical headline: WebP is the first widely supported format that gives you JPEG-like sizes and PNG-like transparency at the same time. A transparent product cut-out that is 900 KB as a PNG can often be a fraction of that as lossy WebP with no visible difference.

Limits worth knowing

  • Maximum size is 16,383 × 16,383 pixels. Larger images must be downscaled or saved in another format.
  • Converting lossy to lossy costs quality. JPEG → WebP → JPEG loses a little at each step. Convert from the best original you have.
  • It is a web format first. Support outside browsers is good and improving, but not universal the way JPEG's is.

When to use WebP

  • Every image on a website you control — photos, screenshots, illustrations. The Image Optimizer converts to WebP, caps the width and strips metadata in one pass.
  • Transparent images on the web, where PNG would be several times larger.
  • Short animations, instead of GIF.

When not to

  • Files you send to other people or organisations. Email recipients, job portals, government forms and printers are safest with JPEG or PNG.
  • Large hero photos where every kilobyte matters. AVIF is usually smaller again, at the cost of slower encoding.
  • Favicons and app icons. Use the formats platforms expect — the Favicon Generator produces them.

Convert WebP files

Each converter runs in your browser with the output format already chosen. Add one file or a whole folder.

Common questions

Drag it into any browser tab, or open it in a current version of Windows Photos or macOS Preview. If an app or website won't accept it, convert it to JPG or PNG.

It can be either. WebP has a lossy mode that works like JPEG and a lossless mode that works like PNG. Both support transparency.

For images on a website, usually: it keeps transparency and is typically much smaller. For files you hand to other people or software, PNG is more widely accepted.

Some upload forms only allow JPEG and PNG. Convert the file to JPG (for photos) or PNG (for graphics with transparency) and upload that instead.

Tools for WebP files

Image ConverterConvert between JPG, PNG, WebP and AVIF with control over quality, transparency and background colour.Image OptimizerOne-pass web optimisation: cap dimensions, pick the best modern format and strip metadata.Image CompressorShrink JPG, PNG and WebP files by quality or to an exact target size, with a side-by-side quality check.Batch Image ToolsApply resize, compression, conversion and watermarks across dozens of images, then export a ZIP.

Keep reading

All image formats