WebP at a glance
WebP is an image format developed by Google and released in 2010. It supports lossy and lossless compression, transparency, and animation. WebP is supported by all modern desktop and mobile browsers, which makes it one of the safest modern formats for production websites.
For most website images, WebP produces noticeably smaller files than JPEG and PNG. A photographic JPEG can often be converted to WebP with a 25-35% file-size reduction at a comparable visual quality. PNG images with flat colors and transparency can become dramatically smaller in WebP.
AVIF at a glance
AVIF is based on the AV1 video codec and delivers some of the strongest compression available for still images. It supports high dynamic range, wide color gamut, transparency, and animation. In many comparisons, AVIF files are 20-50% smaller than JPEG at similar quality and often smaller than WebP as well.
The trade-off is support and encoding speed. AVIF is supported by current versions of Chrome, Edge, Firefox, Safari, and Android browsers, but it is not supported by older browsers or most email clients. Production sites usually pair AVIF with a WebP or JPEG fallback.
Side-by-side comparison
| Feature | WebP | AVIF |
|---|---|---|
| Lossy compression | Yes | Yes |
| Lossless compression | Yes | Yes |
| Transparency | Yes | Yes |
| Animation | Yes | Yes |
| High dynamic range | Limited | Yes |
| Modern browser support | Broad | Good but newer |
| Email client support | Limited | Very limited |
| Typical compression | Smaller than JPEG | Often smaller than WebP |
| Encoding speed | Fast | Slower |
When to use WebP
- Your audience includes older browsers or a wide range of devices.
- You need reliable support across web platforms, CMS uploads, and CDNs.
- You want one modern format that works for both photographs and graphics.
- You are building a site that should work without complex fallback configuration.
- You need to convert a large library quickly with predictable results.
When to use AVIF
- You want the smallest possible files for a modern, performance-focused audience.
- You can provide WebP or JPEG fallbacks through
<picture>or your CDN. - You are serving photography or rich imagery where AVIF quality gains are most visible.
- You need high dynamic range or wide color gamut delivery.
- Your testing shows AVIF produces meaningful savings without visible artifacts.
How to convert without breaking your site
The safest approach is to keep the original high-quality image, create a WebP version for broad support, and optionally create an AVIF version for browsers that support it. In HTML, the <picture> element lets the browser choose the best supported source:
<picture> <source srcset="photo.avif" type="image/avif"> <source srcset="photo.webp" type="image/webp"> <img src="photo.jpg" alt="Descriptive image text" width="1200" height="800"> </picture>
This pattern works in every browser. Modern browsers download the AVIF or WebP source, while older browsers and some crawlers still receive the JPEG fallback.
Quality and file-size testing
Do not assume one format always wins. Compression depends on the source image. A noisy product photo may compress differently than a clean illustration. Test each image type at several quality levels and compare the file size, visible artifacts, and rendering time. A useful target is the smallest file where the image still looks professional on a normal screen and a high-density screen.
Recommendation summary
Try it with the format converter
Use the free image format converter to create WebP and AVIF versions from the same original, then compare file sizes before choosing your production format.
Frequently asked questions
Is AVIF always smaller than WebP?
Usually yes, but not always. The size difference depends on the image content, encoder settings, and quality target. Test each image rather than relying on a general rule.
Does WebP support transparency?
Yes. WebP supports an alpha channel, which makes it a good replacement for PNG when a small file with transparency is needed.
Can I use AVIF in email?
Most email clients do not support AVIF. JPG, PNG, and GIF remain the safe choices for email campaigns.
Which format is better for SEO?
Search engines can index WebP and AVIF, but file size and page speed matter more than the format label. Choose the smallest high-quality file your audience can reliably render.