AVIF and WebP are both designed to replace JPG and PNG for web use — smaller files, better quality, modern compression. The question of which to use is worth understanding properly, because the answer isn't the same for every situation and the tradeoffs are specific enough to matter in practice.
How they differ technically
WebP was developed by Google and released in 2010, making it the older of the two. It uses VP8 compression, supports transparency and animation, and has had universal browser support across Chrome, Firefox, Safari, and Edge for several years. Encoding is fast, decoding is efficient, and the format is well-understood by the tooling ecosystem.
AVIF is derived from the AV1 video codec, developed by the Alliance for Open Media. It achieves better compression than WebP — typically files are 20–50% smaller at equivalent visual quality — and supports wider colour gamuts, HDR, and 10-bit colour depth, which matters for high-fidelity photography and display-quality imagery. The tradeoff is encoding speed: AVIF takes considerably longer to encode than WebP, which becomes a real constraint when processing large batches or generating images server-side at request time.
Browser support today
WebP is fully supported across all current major browsers without qualification. AVIF is supported in Chrome, Firefox, Edge, and Safari 16 and later — which covers the vast majority of current browser usage. The gap in support is primarily with older browsers and software outside the browser context: some image editors, CMS platforms, and email clients still don't handle AVIF reliably.
If your analytics show that your audience is almost entirely on modern browsers, AVIF is a safe primary format. If you have a meaningful portion of older browsers, or if the images will be used outside a web context, WebP is the more reliable default.
The practical middle ground
The HTML <picture> element lets you serve AVIF where supported and fall back to WebP or JPG for browsers that don't handle it:
<picture>
<source srcset="image.avif" type="image/avif">
<source srcset="image.webp" type="image/webp">
<img src="image.jpg" alt="Description of the image">
</picture>This approach gives you AVIF's compression benefits where available without breaking the experience for anyone on an older browser. The downside is maintaining multiple versions of each image — for sites with large image libraries, the storage and workflow overhead may outweigh the compression gains over WebP alone.
A simpler middle ground for most sites: use WebP as the standard format, which already represents a substantial improvement over JPG, and revisit AVIF when it's universally supported without fallback complexity.
When each format is the better choice
AVIF is the better choice for large, complex photographs where maximum compression matters — hero images, high-resolution product photos, background images — on sites targeting modern browsers. Its HDR and wide colour gamut support also makes it the right choice for professional photography or display-optimised imagery where colour accuracy matters.
WebP is the better choice when you need animation support (AVIF's animation support is limited and not widely implemented), when encoding speed matters for your workflow, when broad compatibility is required without fallback complexity, or when images will be used outside a browser context where AVIF support is uncertain.
For icons, thumbnails, and UI elements — images that are already small — the difference between AVIF and WebP in absolute file size is minimal. The format choice matters most for large, complex images where the compression advantage translates to meaningful byte savings.
Converting to either format
Portimg's image converter handles conversion to both WebP and AVIF from JPG, PNG, and other formats in the browser without any software installation. For batch conversion of multiple images, upload them together and download the results as a ZIP. For recurring high-volume conversion workflows, a command-line tool like ImageMagick or a CDN with built-in image optimisation handles it more efficiently than browser-based tools.