Will WebP, AVIF, or JPEG XL make your photo smaller?

Often, yes. You don’t have to shrink a photo’s dimensions to shrink its file. Here’s how to find a smaller copy that still looks right and opens where you need it.

FluffyBench · 6 min read · Reviewed October 15, 2026

Can changing a photo’s format save space?

Yes. Think of each format as a different way of packing the same suitcase: how tightly it packs depends on what’s inside. Changing the format gives your photo a different packing method; the finished file tells you how much room it takes.

We saved a mountain photo as WebP, AVIF, and JPEG XL in FluffyBench Image Space Saver. All three copies were smaller than the original JPG, and JPEG XL saved the most space.

Stanton Mountain reflected in Lake McDonald, the original photo used for the size comparison. — One photo, maximum quality 92, original dimensions, and no file-size cap; this compares bytes, not equal visual quality. How we reviewed · Photo: GlacierNPS / National Park Service, Public domain in the United States; National Park Service employee work, via Wikimedia Commons.

A useful format choice gives you a smaller copy that looks right and opens in your receiving app. A format change can also make other pictures larger— here’s why image files can get larger.

Doing it in FluffyBench Image Space Saver

Start with your original photo in FluffyBench Image Space Saver.

Step 1. Choose your original photo. Keep it for later edits.
1. Choose images opens your file picker.
Step 2. Open Settings to choose how the copy is saved.
1. Settings opens the controls.
Step 3. Choose Custom under Profile to reveal the format and quality controls.
1. Custom lets you choose the settings yourself.

Choose a format your receiving app or upload form accepts. These settings let you compare formats without resizing the picture or searching for a size target.

Step 1. Choose WebP, AVIF, or JPEG XL in Format; it sets the saved file type.
1. WebP is the choice shown here.
Step 2. Maximum quality balances fine detail against file size. Use 92 for this example.
1. Set Maximum quality to 92.
Step 3. Leave Size at Original to keep the same pixel dimensions.
1. Original leaves the picture at its current dimensions.
Step 4. Leave Limit each file’s size unchecked for a format comparison; enabling it adds a size target.
1. Unchecked means there’s no per-file size target.

Each photo gets a tile that shows its size before and after processing.

Step 1. Tap Settings again to close the controls.
1. Settings closes the panel.
Step 2. Before processing, Est. ~ is an estimate of the copy’s size.
1. Est. ~ appears before a finished file exists.
Step 3. Press Process 1 image to make the copy with your chosen settings.
1. Process 1 image starts the conversion.
Step 4. After processing, compare the finished size with the original, then save the copy.
1. The original’s size is shown here.
2. This is the finished file’s size.
3. Download saves this image to your device.

Why can the size shown before you press Process be off? FluffyBench Image Space Saver can estimate from small squares spread across your picture, and those squares can compress differently from the whole photo.

Nine marked areas across the mountain photo, followed by two proportional bars: estimated WebP 444.4 KB and finished WebP 591.1 KB. — The mountain photo’s WebP estimate came in below its finished size. For sufficiently small outputs, Image Space Saver uses the whole image for its estimate. · Photo: GlacierNPS / National Park Service, Public domain in the United States: National Park Service employee work; Public Domain Mark, via Wikimedia Commons.

Does the smaller copy still look right?

Check fine detail in the downloaded picture at the size you’ll use it. Here’s the same patch of mountain and trees in the original JPG and copies saved as WebP, AVIF, and JPEG XL through the current interface.

The mountain photo with a wide detail region marked, above matching original JPG, WebP, AVIF, and JPEG XL crops. — Rendered for illustration at quality 92 and original dimensions. Complete files: original JPG 678.2 KB, WebP 591.1 KB, AVIF 621.9 KB, JPEG XL 511.4 KB. Open your downloaded copy in its receiving app to check that the format works there. · Photo: GlacierNPS / National Park Service, Public domain in the United States: National Park Service employee work; Public Domain Mark, via Wikimedia Commons.

Unsure which format to send? Choosing between AVIF, WebP, and JPEG XL helps you decide.

How we reviewed

Reviewed October 15, 2026

The output bytes, action times and estimate arithmetic in this guide come from the measurement record: three runs per format and browser on 15 October 2026, on Chromium 153.0.8010.12 and Firefox 155.0 in a local build. The JPEG XL comparison was measured on 15 October 2026 with the earlier encoder. Single-file runs of Space Saver, driven against the local preview build. One reference photograph, maximum quality 92, resize off and file-size limit off. Each output format ran three times in a fresh page and the exact output blob bytes were counted. The action time is an end-to-end observation from the run click to the page reporting completion, so it includes interface and polling overhead and not encoder time alone. The pending estimate was reproduced from the tool's own logic: nine 128-pixel squares spread in a three by three grid over the input are encoded in the destination format and quality, and those bytes are scaled to the output area.

Tested on Windows 11, shared desktop machine. The chart uses the Chrome output bytes from the dated run above; Firefox’s WebP was 594.4 KB, and its AVIF and JPEG XL sizes matched Chrome’s. Current UI screenshots and the four-format inspection plate are rendered for illustration, separately from those measurements. Their sizes come from the downloaded files; they do not replace the dated comparison.

The runs covered one photograph and no HEIC input, no batch, no sweep of file-size targets or resize settings, and no comparison at equal visual quality. No visual preference or perceptual quality score was captured, and although the JPEG XL and AVIF bytes were counted, those files were not decoded and checked independently.

The estimate in the dated run used 26.7 KB of encoded sample data. Calculation: sample bytes × output width × output height ÷ sample edge squared.

Saved bytes equal input bytes minus output bytes. The saving percentage divides saved bytes by input bytes.

Displayed sizes use decimal units and one decimal place; exact byte counts appear in accessible labels and titles.

Median action times (Chrome / Firefox): WebP 1,115 ms / 1,193 ms; AVIF 8,779 ms / 6,415 ms; JPEG XL 10,002 ms / 7,901 ms. Chrome JPEG XL times ranged from 9,639 ms to 13,543 ms. Action times include the interface and polling wait, not encoding alone.

Image credits

Stanton Mountain reflected in Lake McDonald — GlacierNPS / National Park Service. Public domain in the United States: National Park Service employee work; Public Domain Mark. The reference photo carries the measured nine-square sample grid; its arithmetic and WebP output come from the local Space Saver run.