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WebP vs AVIF: The Next-Gen Format Battle

WebP was supposed to be the future of web images. Then AVIF showed up with even better compression. Now you're wondering which one to use.

The quick answer: WebP for broad compatibility, AVIF for maximum compression—or serve both and let browsers pick.

Compression Comparison

AVIF typically produces files 20-30% smaller than WebP at equivalent visual quality. For the same image:

  • JPG: 200 KB
  • WebP: 120 KB
  • AVIF: 85 KB

That's a 60% reduction from JPG. For bandwidth-sensitive applications or sites with lots of images, AVIF is compelling.

Browser Support (Late 2024)

WebP

  • Chrome: Yes (since 2014)
  • Firefox: Yes (since 2019)
  • Safari: Yes (since 2020)
  • Edge: Yes
  • Coverage: ~96% of users

AVIF

  • Chrome: Yes (since 2020)
  • Firefox: Yes (since 2021)
  • Safari: Yes (since 2023)
  • Edge: Yes
  • Coverage: ~92% of users

That 4% difference matters less than it used to. Safari was the last major holdout, and now even that supports AVIF. The gap is mostly older browser versions that people haven't updated.

Quality Differences

Both formats can produce visually identical results to the source. But they handle certain content differently:

  • Photographs: AVIF has a slight edge, especially at lower quality settings where WebP can show blocking artifacts.
  • Graphics with sharp edges: Similar performance. Neither introduces obvious artifacts.
  • Gradients: AVIF handles smooth gradients better. WebP can show banding at aggressive compression.
  • Transparency: Both support it. AVIF tends to produce smaller files.

Encoding Speed

Here's where AVIF falls short: it's slow to encode. Creating AVIF files can take 10-20x longer than WebP. For a single image, that's a few extra seconds. For thousands of images, it's a significant time investment.

This matters less for static sites (encode once, serve forever) and more for applications that generate images on the fly.

When to Use WebP

  • You need maximum browser compatibility
  • You're encoding images dynamically and speed matters
  • Your CDN or image service doesn't support AVIF yet
  • The extra compression from AVIF doesn't justify the complexity

When to Use AVIF

  • You're optimizing a high-traffic site where every KB matters
  • You can pre-encode images (not generating them on the fly)
  • Your audience uses modern browsers (internal tools, tech-savvy users)
  • You're serving both formats with WebP/JPG fallback anyway

Serving Both Formats

The cleanest solution is to serve multiple formats and let browsers pick what they support:

<picture>
  <source srcset="image.avif" type="image/avif">
  <source srcset="image.webp" type="image/webp">
  <img src="image.jpg" alt="...">
</picture>

Browsers that support AVIF get the smallest file. Those that don't fall back to WebP. Ancient browsers get JPG. Everyone wins.

The downside: you need to generate and store three versions of every image. CDNs like Cloudflare and Fastly can do this automatically, which makes it easier.

The Practical Answer

For most sites today, WebP is the sweet spot. It's well-supported, encodes quickly, and significantly smaller than JPG. AVIF is worth considering if you're already doing multi-format serving or if you're optimizing a very high-traffic site.

Need to convert? Convert to WebP or convert to AVIF.