Image format tester
Drop in your own photo and see it as JPEG XL, AVIF, WebP and JPEG side by side: how much smaller each one is, how it looks, and whether your browser can show it. Everything runs in your browser, so nothing is uploaded.
Each format gets settings that look broadly alike at that level.
The longest side. Bigger images take longer, mostly for AVIF.
Runs entirely in your browser. Your image is never uploaded or stored.
At these settings
Every format, for your image
| Format | Size | Against JPEG | Encode time | Your browser | File |
|---|
Side by side
Use them on your site
Serve the smallest format each browser can show, with JPEG as the fallback. Copy this, then add the files you downloaded.
How the tester works
Your browser opens the image, resizes it to the size you choose and encodes it four times, with the same open-source encoders Google's Squoosh uses: MozJPEG for JPEG, libwebp, libavif and libjxl. HEIC photos from an iPhone are opened with libheif in browsers that cannot show them. Each format gets settings that look broadly alike at the quality level you pick, so the sizes compare like for like. Nothing leaves your device.
File size is only half the story: check the side-by-side view, because some formats keep fine detail better than others at the same size. For the full comparison, with browser support and when to use each, read our guide to WebP vs AVIF vs JPEG XL.
Image formats: your questions answered
For most photos, AVIF gives the smallest files, with JPEG XL close behind and WebP next. The safest set-up is to serve AVIF or JPEG XL to browsers that can show them, with WebP or JPEG as the fallback, using a picture element. The tester shows which wins for your own image, because the answer changes with the picture.
Increasingly. Chrome 155 (6 October 2026) and Firefox 158 (13 October 2026) were the first versions to show JPEG XL by default, and Safari has shown still JPEG XL images since version 17. Older browsers still cannot, so always keep a fallback. The tester checks your own browser live.
AVIF is usually smaller than WebP at a similar look, often by a fifth or more for photos, but it takes longer to encode. WebP is supported almost everywhere and is a good fallback. Run your own image through the tester to see the difference for your pictures.
No. The image is opened, resized and encoded inside your browser, using open-source encoders that download with the page. Nothing is sent to us or anyone else.
AVIF encoders work hard to squeeze out every byte, so a large photo can take several seconds, and longer on a phone. That cost is paid once, when the image is made, not by your visitors. Choose a smaller size to speed it up.
Download the files, then use a picture element with a source for each modern format and a JPEG as the img fallback; the tester writes the code for you. Many website builders and image CDNs can also convert images automatically.
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