Why WebP Images Make Websites Faster

WebP makes websites faster for a simple reason: it stores the same picture in fewer bytes than JPG or PNG. Images are usually the heaviest part of a web page, so smaller images mean less to download, a sooner-visible main image, and better loading scores. Switching your photos to WebP is one of the easiest speed improvements you can make without redesigning anything.

How Much Smaller WebP Files Are

Google, which developed the format, publishes its own comparisons. According to the WebP documentation:

• Lossy WebP images are about 25–34% smaller than comparable JPG images.
• Lossless WebP images are about 26% smaller than PNGs.

Your own savings will vary with the image and the quality you choose. Photos with large smooth areas often shrink more; images that are already heavily compressed shrink less. The only reliable way to know is to convert a few of your own images and compare the file sizes.

Why WebP Compresses Better

Lossy WebP is based on the intra-frame coding used in the VP8 video codec. A few techniques give it an edge over the much older JPG standard:

• Block prediction. WebP predicts each block of pixels from neighbouring blocks that have already been decoded, then stores only the difference. In smooth areas such as sky or a studio backdrop, that difference is tiny.
• More efficient entropy coding. WebP uses arithmetic coding, which packs the compressed data more tightly than the Huffman coding baseline JPG uses.
• Adaptive filtering. A built-in filter smooths the edges between blocks, which reduces the blocky look that over-compressed JPGs get.
• Lossless mode for graphics. WebP has a separate lossless mode that rivals PNG and is usually smaller, so one format covers photos and graphics.
• Transparency with lossy compression. A product cut-out can be a small lossy WebP with a transparent background. With older formats you had to use a large PNG.

How Smaller Images Speed Up a Page

Byte savings turn into speed in a few concrete ways:

• Faster Largest Contentful Paint (LCP). On many pages the largest visible element is a hero image or featured photo. A smaller file arrives sooner, and LCP is one of Google's Core Web Vitals.
• Less competition for bandwidth. On a mobile connection, every image competes with scripts and fonts. Less image data frees up the connection for everything else.
• Lower data costs for visitors on metered plans and lower bandwidth bills for you.

The format is only one lever. A 4000-pixel-wide WebP in an 800-pixel column is still wasteful, so resize to the displayed size as well. Our image optimization guide for websites covers resizing, lazy loading and responsive images together, and how to optimize images for SEO covers file names, alt text and the LCP image.

When Not to Use WebP

WebP is the right default for images on your own website, but it is not the best choice everywhere:

• Print. Many print shops and layout programs expect JPG, TIFF or PDF.
• Uploads to forms and marketplaces. Government portals, exam forms and some marketplaces accept only JPG or PNG. Check the rules first.
• Email attachments and sharing. Recipients may open them in older software. JPG is safer.
• Editing masters. Keep your original or a lossless PNG for editing, and export WebP as the final step.

If you receive a WebP that won't open somewhere, convert it with WebP to JPG.

Browser Support

All current versions of Chrome, Edge, Firefox and Safari display WebP, as do the major mobile browsers (caniuse WebP). Safari added support in version 14. The holdouts are Internet Explorer and old Safari versions on devices that can no longer update.

For most sites, using WebP directly in an <img> tag is fine. If you still need to support very old browsers, the <picture> element lets the browser choose:

<picture>
  <source srcset="photo.webp" type="image/webp">
  <img src="photo.jpg" alt="Describe the photo" width="1200" height="800">
</picture>

Browsers that understand WebP download the WebP; others fall back to the JPG. Always include width and height so the browser reserves space and the layout doesn't jump while the image loads.

How to Switch Your Site to WebP

Convert Existing Images

1. Export the images from your CMS or server, starting with your most visited pages.
2. Convert them with JPG to WebP or PNG to WebP. The converters run in your browser, so the files are not uploaded.
3. Upload the WebP versions and update the image references in your pages or templates.
4. Keep the originals in case you need other sizes or formats later.

Start from the highest-quality version you have. Converting an already heavily compressed JPG to WebP stacks two rounds of lossy compression.

Save New Images as WebP

For new content, export WebP directly at a quality of around 75–85 for photos, and compare with the original. The image compressor can output WebP with a quality slider and before/after preview. Our guide on compressing images without losing quality explains how to pick the setting.

Let Your Platform Do It

Many platforms can generate and serve WebP automatically: WordPress image optimisation plugins, image CDNs, the Next.js Image component and the image pipelines in static site generators. If your stack offers this, it is the least effort over time. Check that it doesn't compress again images you already optimised by hand.

Checking That WebP Is Being Served

After you switch, confirm it worked:

1. Open your page in Chrome or Firefox and open DevTools (F12).
2. Go to the Network tab, filter by Img, and reload.
3. Click an image and check the response header Content-Type. It should say image/webp.

Then run the page through PageSpeed Insights before and after the change and compare the LCP figure and the "Improve image delivery" or "Serve images in next-gen formats" suggestions.

WebP Compared with AVIF

AVIF is a newer format that often produces even smaller photos than WebP. It is slower to encode, and fewer tools and upload systems accept it. Some sites serve AVIF first, WebP second and JPG last. For most sites, WebP gives most of the benefit with the fewest compatibility problems. The full comparison is in PNG vs JPG vs WebP vs AVIF.

Frequently Asked Questions

How much smaller is WebP than JPG?

Google reports lossy WebP files are about 25 to 34 percent smaller than comparable JPGs, and lossless WebP is about 26 percent smaller than PNG. Your results depend on the image and the quality setting.

Do all browsers support WebP?

All current versions of Chrome, Edge, Firefox and Safari support WebP. Only very old browsers, such as Internet Explorer and Safari versions before 14, do not. Use the picture element with a JPG fallback if you still need to support them.

Will converting JPG to WebP lower quality?

A lossy conversion discards a little more data, so start from the highest-quality original you have and use a quality around 75 to 85. Compare the result with the original before replacing it.

Does WebP help SEO?

Indirectly. Smaller images can improve loading metrics such as Largest Contentful Paint, which are part of Google's page experience signals. The format alone does not raise rankings; faster pages and a better experience do.