AVIF compresses harder. WebP encodes faster, is supported more widely outside the browser, and you can produce it with the tools you already have.
Raw compression. Typically 20–30% below WebP at matched visual quality, and the gap widens on large images and at low bitrates.
Gradients. 10- and 12-bit colour depth largely eliminates banding across skies and studio backdrops, which is a persistent weakness of every 8-bit format.
Low-quality resilience. At aggressive settings AVIF stays coherent where WebP softens. For thumbnails and blur-up placeholders this is a real advantage.
Encoding time. Often an order of magnitude faster. If images are encoded on demand rather than at build time, this decides it on its own.
Tooling. Every browser can write WebP through a canvas, which is why the tools on this site can produce it and cannot produce AVIF. Desktop and server support is also broader.
Decode cost. Lower, which matters on cheap phones rendering a long grid of images.
Small files. Below roughly 10 KB, AVIF's container overhead frequently makes it the larger of the two.
The <picture> element resolves the argument entirely. Offer AVIF, then WebP, then JPEG, and every browser takes the best it understands:
<picture>
<source srcset="photo.avif" type="image/avif">
<source srcset="photo.webp" type="image/webp">
<img src="photo.jpg" alt="Description" width="1600" height="1067">
</picture>The cost is generating and storing three files instead of one. Whether that is worth 20–30% on top of what WebP already saved is a question about your traffic and your build, not about which format is better.
Everything below runs in your browser, so you can test any of this on your own files without uploading them.
Re-encode existing WebP files, or convert JPEG and PNG into WebP.
Open the toolTypically 25–35% smaller at matched quality. The standard web win.
Open the toolOne setting across a whole folder, processed in parallel, downloaded as a ZIP.
Open the toolShrink JPG and JPEG photographs with a quality slider or an exact target size.
Open the toolQuestions
Every answer below is present in the page source, expanded, so it can be read without opening anything.
WebP. It captures the majority of the available saving over JPEG, encodes quickly enough for any workflow, is supported everywhere including in browser tooling, and never surprises you on small files.
Because these tools encode through your browser's canvas, and browsers expose a WebP encoder but generally not an AVIF one. Rather than offer an AVIF option that would silently return a PNG, the tools probe what your browser can actually write and disable anything it cannot.
For a build pipeline that runs once per image and serves it thousands of times, easily. For on-demand encoding, almost never — the latency cost lands on every request while the byte saving is modest on top of WebP.
Yes, both carry a full alpha channel, and either can replace PNG for transparent graphics on the web.
AVIF, clearly. Its 10- and 12-bit colour depth gives far more intermediate values than WebP's 8-bit, so wide gradients such as skies band much less.
Technically impressive — particularly its ability to losslessly repack an existing JPEG about 20% smaller — but browser support has not settled, which makes it hard to recommend for production today. AVIF and WebP are the practical choices.
From the blog
Longer, more practical guides from the blog.
WebP produced a 27.0 KB file against MozJPEG's 41.1 KB on the same photograph at slightly higher measured fidelity — 34% smaller. It also produced a larger file than JPEG on random noise. The advantage is real and content-dependent.
9 min read
Resize before you compress. Measured on one photograph: half the width at quality 80 produced a 16.4 KB file, while full width at quality 40 produced 20.6 KB and looked far worse. The order of operations matters more than the settings.
8 min read
PNG stored the same photograph in 1274.1 KB where JPEG needed 67.5 KB — nineteen times larger. On a flat graphic PNG won. On a smooth gradient PNG lost to JPEG by a factor of two, which surprises most people.
9 min read