Comparing compression ratios is tricky. What you usually want is "file size at same visual quality" or "visual quality as same file size" for comparisons. The p

Comparing compression ratios is tricky. What you usually want is "file size at same visual quality" or "visual quality as same file size" for comparisons. The problem here is that "visual quality" is in the eye of the beholder, Different base images will have different results. There are some attempts at such comparisons, e.g. https://cloudinary.com/blog/how_jpeg_xl_compares_to_other_image_codecs https://cloudinary.com/blog/how_jpeg_xl_compares_to_other_im... (cloudinary might be biased, as they are a major driver behind jpeg-xl) My overall impression is that it's roughly on par or a little behind with AVIF, somewhat ahead of HEIC and very ahead of WEBP (and jpeg of course) in quality-per-byte. As for encode and decode speed, it's a bit slower than WEBP but beats AVIF and HEIC by a margin (unless these codecs are back by hardware encoders). However, all three codecs are relatively new and there may be a lot of future speed optimizations possible. Especially jpeg-xl, which isn't "backed" by general AV1 (AVIF), vpx (WEBP) or HEVC (HEIC) research, may have a particularly large yet to be tapped potential for (hardware-specific) optimizations. As far as I know, jpeg-xl is also "simpler" than those other codecs (which basically used the iframes of their complex sibling video codecs as a base), so it might be more feasible to have more competing implementations. But time will tell, and it will of course also largely depend on the adoption and thus network effects of these formats who much "love" each format receives from open source and proprietary software vendors.