AVIF vs WebP in 2025: Which Format Should You Use?

Two years ago, WebP was the answer to 'what image format should I use on the web?' It's still a good answer. But AVIF has matured to the point where it deserves a serious look.

The Numbers

Real-world comparisons consistently show AVIF 20-50% smaller than WebP at equivalent quality for photographic images. A 200KB WebP becomes roughly 120-160KB AVIF. For a site with hundreds of product photos, this translates directly to faster page loads and lower bandwidth costs.

For graphics with flat colors, icons, and illustrations, the advantage is smaller and sometimes WebP wins on encoding simplicity. AVIF's compression algorithm is optimized for natural images.

The Speed Tradeoff

AVIF encoding is slow. Encoding a single large AVIF image can take 10-30 seconds on a modern machine. The same image as WebP encodes in 1-2 seconds. For small batches this is fine. For processing thousands of user-uploaded images in real time, AVIF encoding is a serious bottleneck unless you have dedicated encoding infrastructure or use a CDN that handles it.

AVIF decoding (displaying in a browser) is fast — comparable to JPEG and WebP. The slowness is only in the encoding process.

The Practical Answer for 2025

Serve AVIF to browsers that support it, WebP as fallback, JPEG as the last resort. Use the picture element:

This serves the best format to every browser. The JPEG fallback is there for ancient browsers and situations where the image is downloaded directly.

If You Use an Image CDN

Cloudflare Images, Cloudinary, and Imgix all support automatic format negotiation — they detect the browser's supported formats from the Accept header and serve the best one. No picture element needed, no manual conversion. This is the most scalable approach and worth the CDN cost for image-heavy sites.