What is the best image format for a website?

"Best format" is the wrong question until you know what the image is. A website carries a few very different kinds of picture, and each has a clear winner:

• Photographs (products, people, places): a lossy format. AVIF is the smallest, WebP is the safe modern default, and JPG is the fallback every browser can show.
• Logos, icons and illustrations: SVG. It is vector artwork, so it stays crisp at any size on any screen, and the file is usually tiny. Fall back to a pixel format only when a platform refuses SVG.
• Screenshots, UI graphics and anything with transparency: PNG, or lossless WebP. Flat color and sharp edges are exactly what lossless formats pack well.
• Short animations: animated WebP or AVIF rather than GIF, which is limited to a small palette and produces far larger files.
• The favicon: an ICO file, ideally alongside an SVG or PNG version — see how to create a favicon from an image.

The classic mistake is a photograph saved as PNG. PNG stores every pixel losslessly, which is perfect for a logo and disastrous for a photo: the file balloons to several times the size of a JPG with no visible gain.

For photos the choice comes down to how much you can lean on newer browsers:

• AVIF compresses best: at typical web quality it lands around 50% smaller than JPEG and 20–30% smaller than WebP, with HDR and wide-gamut color if you need them. Chrome, Firefox and Safari all display it (Safari since version 16.4, in 2023). The costs are slow encoding, especially on large images, and thin support in desktop software and older devices.
• WebP is the pragmatic default: 25–35% smaller than JPEG at the same visual quality, with transparency, and supported by every mainstream browser since 2020. Some desktop apps and older tools still cannot open it, which matters for the file you hand a designer, not for the one you serve to visitors.
• JPG is the universal fallback. It is the least efficient of the three, but a JPG saved around quality 75–82 is usually indistinguishable from the original on screen, and nothing on the web fails to show it.

The strongest setup serves AVIF to browsers that understand it, WebP to the rest, and keeps a JPG for anything older. If you would rather pick one, WebP with a JPG fallback covers practically everyone. The head-to-head comparisons are in WebP vs AVIF and WebP vs JPG; for graphics rather than photos, see PNG vs JPG.

Once you know the target, the conversion is quick and never leaves your machine. The EditItAll image converter runs entirely in your browser:

1. Open the converter and drop in your images — one file or a whole folder's worth. Batches are processed together.
2. Choose the output format: WebP or AVIF for photographs, PNG for graphics that need transparency. There are direct routes for the common jobs: JPG to WebP, PNG to WebP, JPG to AVIF and PNG to AVIF.
3. Set the quality. There is no target-size field: the size is an output. Each file shows its size before and after, so nudge the slider until the number and the picture both look right.
4. Download the results individually or as a single ZIP.

Nothing is uploaded — you can disconnect from the internet after the page loads and keep converting — and EXIF and GPS metadata are stripped from every exported image, so a product photo does not publish where it was taken. It is free, with no account and no watermark. Already have the right format and just need it smaller? Go straight to the image compressor. And if a platform insists on a pixel version of a vector logo, SVG to PNG renders it at whatever size you choose.

Format choice is worth doing, but three habits save more bytes than switching from JPG to AVIF ever will:

• Resize to the size you actually display. A camera photo is many times wider than the space it fills on a page, and every one of those extra pixels is downloaded and thrown away. The EditItAll image tools have an optional maximum-dimension cap for exactly this.
• Compress once, from the original. Every lossy save discards a little more detail. Keep the original, export the web copy from it, and do not re-save a JPG as a WebP as an AVIF in a chain.
• Serve modern formats with a fallback. Offer AVIF or WebP first and let older browsers fall back to JPG or PNG, so no visitor ever sees a broken image.

If a speed report tells you to "efficiently encode images" or "serve images in next-gen formats", this decision is precisely what it means: fixing the efficiently encode images warning walks through it, and compressing JPEG for the web covers the quality slider in detail. More format guides live in the converting images cluster.