Why is the JPG bigger than the AVIF?

AVIF compresses far better than JPG, so a JPG needs more bytes for a similar look. That's expected.

Does my browser need AVIF support?

No. If your browser can't decode AVIF natively, a built-in decoder takes over.

No. JPG output here is standard range, so HDR highlights are mapped to a normal range.

No. Converting happens in your browser with WebAssembly, so nothing is sent to a server.

AVIF to JPG

Turn AVIF images into JPGs for software that can't open them yet.

Runs on your device. Nothing is uploaded.