WebP vs AVIF: How to Choose and Test the Right Image Format

AVIF can beat WebP for some images and quality targets; WebP can be faster to encode and may fit a broader legacy workflow. Neither result is guaranteed by the extension. Compare representative outputs, compatibility, and pipeline cost, then provide fallbacks where your audience needs them.

The Two Formats at a Glance

Both WebP and AVIF were born from video codecs. Google released WebP in 2010 based on VP8, the same technology behind its WebM video format. The Alliance for Open Media released AVIF in 2019 based on AV1, a newer and more efficient video codec developed collaboratively by Google, Mozilla, Apple, Netflix, and others.

The newer coding tools available to AV1 can improve compression, while WebP’s simpler and mature implementations can reduce processing cost. Actual encoding and decoding behavior depends on the codec implementation, settings, image features, and device.

Compression: How Much Smaller Are the Files?

Benchmark outcomes vary with the corpus, encoders, effort settings, source history, and quality metric. A responsible test keeps dimensions and metadata policy consistent and compares several visual metrics plus human review:

• AVIF — can deliver a strong result for photographs, gradients, HDR, and high-bit-depth workflows, but encoding may be expensive
• WebP — can deliver efficient lossy or lossless output with mature tooling and lower operational complexity in many pipelines

Do not convert one format’s marketing average into a per-file forecast. Export both from the same master, choose comparable visual quality, and include encoding time, decode behavior, metadata, and fallback transfer in the decision.

Non-photographic assets can behave differently from photo benchmarks. For simple graphics, icons, and flat illustrations, compare lossless or near-lossless candidates where supported; either format can win depending on palette, alpha, encoder, and settings.

Browser and Software Support

Support tables change and global share is not the same as your audience. Check target browsers and non-browser consumers. The <picture> element can offer AVIF first, then WebP, with JPEG as the final <img> fallback:

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

Encoding Speed and Tooling

WebP encoders often require less computation than AVIF encoders at comparable effort settings, but the ratio varies widely. If a CMS converts images on upload or in large batches, benchmark throughput, memory, queue time, and output quality with the exact libraries and settings you deploy.

Encoder performance changes across libraries and releases. Decode cost also depends on dimensions, bit depth, device, browser, and implementation. Test low-end target devices rather than assuming a difference is imperceptible.

Tooling support is broad but uneven. Confirm import, export, animation, color profile, metadata, and automatic negotiation behavior in the exact editor, CMS, CDN plan, and browser stack you use.

Feature Comparison

AVIF can represent higher bit depths, wide-gamut color, and HDR signaling beyond WebP’s 8-bit coding. That capability does not guarantee color accuracy: mastering, profiles, metadata, browser behavior, display capability, and testing still matter.

When to Use Which Format

Choose AVIF when:

• You control the image pipeline and can serve fallbacks
• Representative AVIF outputs improve the relevant transfer or quality bottleneck
• You need AVIF capabilities such as higher-bit-depth or HDR workflows and have tested the complete color path
• Your CDN or build pipeline generates, caches, and negotiates verified variants correctly

Choose WebP when:

• Your measured encoder throughput or operational simplicity favors WebP
• Your supported clients accept WebP and the extra AVIF variant is not justified
• Your representative graphics meet their byte and quality targets in WebP
• You're already serving WebP and the migration effort isn't justified

Use both when the measured benefit justifies it:

A <picture> stack adds generation, storage, caching, markup, and quality-review work, but can improve delivery. Some CDNs automate negotiation; verify plan behavior, cache keys, Vary handling, quality settings, and fallback output rather than assuming “optimal” delivery.

How to Convert Your Images

Vizua can create supported WebP and AVIF outputs in the browser without a software installation. The selected file is not sent to our image-processing server; required code and site services may still use the network:

• Compress WebP — reduce existing WebP files
• Convert to AVIF — create AVIF from supported input images
• JPG to WebP — convert your JPEG photos to WebP
• PNG to WebP — convert PNG graphics to WebP

If you are working with JPEG sources, our guide to compressing images without losing quality explains how to choose starting settings and compare actual outputs.

Frequently Asked Questions