Honest, tested guides on the image formats that matter in 2026 — and the page-speed rules that come with them.
These guides answer two questions that come up whenever someone tries to make a page load faster. First, which file format should the image actually be — and the answer is almost never the format you started with. Second, how do you get from the file your camera produced to the file a browser can load quickly, without losing the detail that matters.
Every number here was produced by running the measurement on this site, and each article states the month it was tested, because codec support and browser behaviour change. The 50-photo shootout is the best single starting point if you want one data point to decide from. If your problem is specifically that a tool you were using stopped moving, read the Squoosh situation. If you only want the answer to one conversion, JPG to WebP covers the numbers you need, and if a page is slow enough to cost you visitors, start with the Core Web Vitals guide.