WebP vs AVIF | Which Image Format Should You Choose in 2025?

WebP and AVIF are the two dominant next-generation image formats for the web. Both compress better than JPEG and PNG, both are widely supported by modern browsers. But they are not interchangeable. Choosing the wrong one means either leaving performance gains on the table or shipping broken images to a fraction of your users.

This guide cuts through the noise: technical comparison, real-world benchmarks, a decision matrix by use case, and a ready-to-copy HTML implementation.

What Is WebP?

WebP was developed by Google and released in 2010, based on the VP8 video codec. It supports both lossy and lossless compression, transparency (alpha channel), and animation. It became the de facto standard for web images once Safari added support in 2020.

Browser support (2025): 97% global coverage.

What Is AVIF?

AVIF (AV1 Image File Format) is derived from the AV1 video codec, developed by the Alliance for Open Media. It was designed from the ground up for high-fidelity, high-efficiency image compression. It supports 10-bit and 12-bit color depth, HDR, wide color gamut, and both lossy and lossless modes.

Browser support (2025): 93% global coverage. Not supported in older Edge versions and some minor mobile browsers.

Compression | Which Format Is Smaller?

In most benchmarks, AVIF achieves 20 to 50% smaller file sizes than WebP at equivalent visual quality. The gap is most noticeable on photographic content.

For a typical 500 KB hero image compressed to quality 80:

• JPEG: 500 KB
• WebP: ~340 KB (-32%)
• AVIF: ~240 KB (-52%)

These numbers vary depending on content type. AVIF's advantage shrinks on simple graphics, flat illustrations, and icons.

Quality | Artifacts and Visual Fidelity

At high compression ratios, AVIF produces significantly fewer artifacts than WebP. WebP at very low quality settings tends to introduce blocky, mosaic-like distortions. AVIF degrades more gracefully, preserving edges and fine textures better.

AVIF also supports 10-bit color depth natively, which eliminates color banding in gradient-heavy images (skies, backgrounds). WebP is limited to 8-bit.

For lossless compression, WebP is generally faster and produces comparable results to AVIF.

Encoding Speed | A Real Difference

This is where AVIF pays a cost. Encoding AVIF is significantly slower than encoding WebP, sometimes by a factor of 5 to 10x, depending on the encoder settings and image size.

Decoding speed (i.e., the time the browser takes to render the image) is comparable for both formats. The slowness is on the generation side, which matters for dynamic pipelines but not for static pre-generated assets.

Browser Support | Who Sees What?

WebP is safe to use without a fallback for any audience active in the last five years. AVIF requires more caution if you target older enterprise environments or less common mobile browsers.

If your analytics show significant traffic from IE 11 or very old Safari, keep JPEG as the fallback. For most modern web audiences, AVIF with a WebP fallback is a safe and optimal strategy.

LCP and Core Web Vitals Impact

Image format directly affects Largest Contentful Paint (LCP), one of Google's three Core Web Vitals. Smaller files load faster over the network, which improves LCP scores.

Switching from JPEG to WebP on a hero image typically reduces LCP by 100 to 300 ms on a mobile 4G connection. Switching from WebP to AVIF can shave an additional 50 to 150 ms on the same image.

For sites where images are the LCP element (most e-commerce and editorial sites), this difference is meaningful for both user experience and search ranking.

Decision Matrix | Which Format for Which Use Case?

How to Implement AVIF with WebP Fallback

The <picture> element lets the browser pick the first format it supports. List AVIF first, WebP second, JPEG last.

<picture>
  <source srcset="image.avif" type="image/avif">
  <source srcset="image.webp" type="image/webp">
  <img src="image.jpg" alt="Description of the image" width="800" height="600">
</picture>

The browser downloads only the first matching source. Older browsers that support neither AVIF nor WebP fall back to the <img> JPEG automatically.

For responsive images, combine with srcset and sizes:

<picture>
  <source
    srcset="image-400.avif 400w, image-800.avif 800w, image-1200.avif 1200w"
    sizes="(max-width: 600px) 100vw, 800px"
    type="image/avif">
  <source
    srcset="image-400.webp 400w, image-800.webp 800w, image-1200.webp 1200w"
    sizes="(max-width: 600px) 100vw, 800px"
    type="image/webp">
  <img src="image-800.jpg" alt="Description of the image" width="800" height="600">
</picture>

Summary | WebP vs AVIF at a Glance

Use AVIF when maximum compression and image quality matter: hero images, product photos, editorial content. Always add a WebP fallback via <picture>.

Use WebP when you need fast encoding (dynamic pipelines, CMS), when you serve animations, or when your audience may include older browsers.

The two formats are complementary, not competing. The <picture> element was made for exactly this situation.

Convert Your Images to WebP and AVIF

Morphix converts PNG and JPG images to WebP and AVIF directly in your browser. No registration required for the free plan.

Convert to WebP | Convert to AVIF