WebP Image Converter

Convert images to and from WebP format for faster page loading with quality and size control.

Tested tool guide Tested browser tools Checked August 16, 2026

What WebP Image Converter does and how it behaves

This tool re-encodes an image you drop in as WebP, or decodes a WebP back into PNG or JPEG, entirely in the browser. A quality slider (roughly 0-100) controls lossy compression strength, and it reports the new file size next to the original so you can judge the tradeoff before downloading. What trips people up: the browser's native canvas WebP encoder is lossy-only -- there is no lossless WebP output option available through canvas.toBlob(), so pushing the slider to 100 minimizes visible loss but never produces a byte-exact lossless file. If you need true lossless WebP, this tool can't produce it no matter where the slider sits.

How the result is produced

Encode to WebP

The source image is decoded and drawn to an off-screen canvas, then re-exported through the browser's built-in WebP encoder at the quality value you set. This encoder only supports lossy output -- it discards detail using block-based prediction similar to VP8 video frames -- so the quality value always has some effect on file size, even set as high as it goes.

Decode from WebP

A .webp file is decoded natively by the browser (lossy, lossless, or with an alpha channel) and drawn to canvas, then exported as PNG or JPEG. If the source WebP is animated, the canvas only captures a single frame, so the exported file is a static image even though the original animated.

Good uses

Shrinking a batch of product photos or screenshots before uploading them to a website, to cut page load time
Converting a WebP image saved from a website into PNG or JPEG so it opens in an editor or CMS that rejects .webp uploads
Comparing output file size at a few quality settings before deciding what to actually ship

Limits and checks

Quality near 100 is not the same as lossless -- the browser's canvas encoder can't produce true lossless WebP, so there's no setting that guarantees pixel-perfect output the way a dedicated lossless encoder could
Converting an animated WebP only yields the current or first frame; the exported PNG/JPEG has no animation and the tool gives no warning that frames were dropped
There is no fixed percentage savings for a given quality number; the same quality setting can shrink a smooth photo by 60% and a noisy, detailed image by far less

Common questions

Does converting to WebP keep transparency?

Yes if the output stays WebP or you export to PNG, since both support an alpha channel. If you convert a transparent WebP or PNG to JPEG, JPEG has no alpha channel, so transparent areas get flattened onto a solid background color in the output.

Is my image uploaded to a server to do the conversion?

No. The decode and re-encode happen locally in the browser using canvas APIs, so the file never leaves your device during conversion. This also means very large images are limited by your browser's own memory and canvas size limits, not a server timeout.

References and verification

The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.