WebP vs. AVIF: How to Fix "Serve Images in Next-Gen Formats"

If you have ever run your website through Google PageSpeed Insights, you have likely seen the dreaded recommendation: "Serve images in next-gen formats." In 2026, relying on legacy formats like JPG and PNG is a recipe for slow load times and poor SEO rankings.

But which "next-gen" format should you choose? Today, the battle for the web's visual future is between WebP and AVIF. This guide explains the technical differences, compression efficiency, and how to implement them to achieve a 100/100 performance score.

1. What are Next-Gen Formats?

Traditional image formats like JPEG were developed in the early 90s. They weren't designed for the modern web, where every kilobyte matters. Next-gen formats use advanced compression algorithms originally designed for video (VP8 for WebP and AV1 for AVIF).

The goal of these formats is simple: identical visual quality at a fraction of the file size. When you serve a "Next-Gen" image, you are often reducing the payload by 30% to 80% compared to a traditional JPEG.

2. Deep Dive: WebP (The Current Standard)

Developed by Google, WebP has become the industry standard for modern web development. It supports both lossy and lossless compression, as well as transparency (alpha channel).

Why WebP Wins:

• Universal Support: As of 2026, 97%+ of browsers support WebP, including Chrome, Safari, and Firefox.
• Animation: WebP can replace bulky GIFs with much smaller file sizes.
• Versatility: It handles both photographs and graphics equally well.

3. Deep Dive: AVIF (The Future Leader)

AVIF is the newcomer, based on the AV1 video codec. While it is more computationally intensive to encode (it takes longer to save), the results are spectacular. AVIF can often be 20% smaller than WebP while maintaining higher detail in textures and gradients.

Why AVIF Wins:

• Superior Compression: It is the most efficient image format available in 2026.
• HDR Support: Unlike WebP, AVIF supports high dynamic range (10-bit and 12-bit color), making it perfect for high-end photography sites.
• Fewer Artifacts: At very low bitrates, AVIF blurs rather than creating the "boxy" artifacts seen in JPEGs.

4. Performance Comparison

To help you decide, our engineering team ran a test on a standard 2000px hero image. Here are the results:

5. How to Implement Next-Gen Formats

You don't have to choose just one. The best way to serve next-gen images is via the <picture> element in HTML. This allows you to serve AVIF to browsers that support it, with a WebP or JPEG fallback for older devices.

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

6. Impact on SEO and Core Web Vitals

Google’s Largest Contentful Paint (LCP) is heavily weighted by image load time. By switching from JPEG to AVIF or WebP, you are directly improving your LCP. In competitive niches, a site that loads 1 second faster can be the difference between a Rank #1 and Rank #5 spot.

Furthermore, smaller images reduce **Total Blocking Time (TBT)** because the browser spends less time decoding and decompressing the visual data from the network stream.

Summary: WebP or AVIF?

In 2026, the best strategy is a hybrid one. Use **AVIF** for your largest hero images and product galleries to maximize compression. Use **WebP** as a universal modern fallback. By removing legacy formats from your critical rendering path, you ensure your website stays fast, user-friendly, and search-engine optimized.