Convert JPG to AVIF

AVIF gives the smallest files, at a cost

AVIF uses AV1 coding and compresses a photograph more efficiently than either JPG or WebP, typically reaching 20 to 50 percent smaller than WebP at an equivalent appearance. That is a real advantage for a page with many images. The costs are honest ones: encoding is significantly slower, and support, while good, is not universal in older browsers and in a number of design and content systems.

MDN: image file type and format guide

The fallback is not optional in most cases

A browser that does not support AVIF does not show a degraded image, it shows nothing at all. That is a worse failure than a slightly larger file, which is why the standard implementation serves AVIF and keeps a WebP copy as the fallback. The two files together cost more than one, and that is the deliberate trade: you pay in storage and in requests to guarantee that something appears for every visitor. If you can only upload one file, WebP is the safer single choice.

• Serve AVIF with a WebP fallback and keep both files.
• A browser without AVIF support shows no image, which is worse than a larger one.
• If only one file is possible, choose WebP.
• Check that your CMS accepts AVIF before batch converting.
• Some design tools cannot open AVIF at all.

What AVIF does not carry over

Like every lossy format, a JPG converted to AVIF is a reconstruction, so the quality available is bounded by the JPG you started with. Two further details are worth knowing: AVIF supports a 10-bit channel, which is more than a JPG carries, so that capability is unused here, and it supports smooth transparency, which a JPG does not have. Neither is a reason to convert, but both explain why converting a transparent source such as a PNG is a more meaningful operation.

• Quality is bounded by the lossy JPG you are converting from.
• A second conversion loses a little more. Convert from the original each time.
• AVIF 10-bit depth and smooth transparency are unused when the source is a JPG.
• Converting from a transparent PNG uses those capabilities properly.

When WebP is the better answer

AVIF is the wrong choice in several common situations. If the audience is known to be on older browsers, the fallback costs more than it returns. If a content system, email client, or design tool will not accept it, the file cannot be used at all. If the image is a flat graphic or has text, WebP lossless is a better fit. And if a batch of images will be processed, the slower encoding is a real cost in time.

• Older browser audience: WebP with no fallback needed.
• A CMS or tool that rejects AVIF: WebP.
• Flat graphics or text: WebP lossless.
• Large batches where time matters: WebP, because AVIF encoding is slow.