JPG to WebP file size test
WebP is often recommended as a smaller stand-in for JPEG. We converted eight project photographs with the live JPG to WebP tool. 8 of 8 files shrank on this set. Savings still ranged from modest to extreme, so the format change is not a single percentage.
Why convert at all
Teams switch to WebP for page weight, transparency, or a modern <picture> stack. Photographers still email JPEG. This test only answers the byte question on our encoder: if you hand the public tool a JPG, what WebP do you get back?
Method
Same eight JPEGs as the other research pages. One conversion each. Output dimensions matched the source. We compared disk bytes to generated WebP bytes. We did not tune a quality slider per photo, and we did not include AVIF in this run.
Results
| Subject | Original | Output | Pixels in | Pixels out | Change |
|---|---|---|---|---|---|
| Alpine | 503 KB | 302 KB | 2400×1600 | 2400×1600 | 39.9% smaller |
| Coast | 448 KB | 243 KB | 2400×1595 | 2400×1595 | 45.8% smaller |
| Forest | 1.09 MB | 928 KB | 2400×1598 | 2400×1598 | 17.2% smaller |
| City | 730 KB | 449 KB | 2400×1600 | 2400×1600 | 38.5% smaller |
| Ceramic | 293 KB | 130 KB | 2400×1600 | 2400×1600 | 55.6% smaller |
| Books | 406 KB | 185 KB | 2400×1551 | 2400×1551 | 54.3% smaller |
| Flower | 502 KB | 237 KB | 2400×1601 | 2400×1601 | 52.7% smaller |
| Watch | 106 KB | 37.3 KB | 2400×1744 | 2400×1744 | 64.7% smaller |
Reading the spread
Ceramic dropped from 293 KB to 130 KB. Watch dropped from 106 KB to 37.3 KB. Those still-life frames have larger flat areas than the forest or alpine landscapes, and the default WebP encode stored them more cheaply.
City still saved (730 KB JPEG to 449 KB WebP), but alpine (503 KB to 302 KB) and forest (1.09 MB to 928 KB) show that busy landscapes keep more weight. A conversion that often saves is not a single percentage. Read the result card.
A tiny, already-quantized JPEG can still grow if a high-quality WebP rewrite stores more residual detail. That case did not appear in these eight rows. We are not generalizing beyond this set.
Practical conclusion
Convert when you need a WebP file, then read the generated size. If the destination is a JPEG-only upload field, stay on JPEG and use a target-size compressor instead. For the public format overview, start at JPG to WebP.
Limits
No visual MOS scores. No lossless WebP trial. No AVIF column. Eight photos, one quality preset. Browser support for WebP is wide on current engines; this page is about bytes, not compatibility charts.
Technical reference
WebP is documented by Google, including lossy, lossless, animation, and alpha: developers.google.com/speed/webp. MDN’s image type guide places WebP next to JPEG, PNG, and AVIF. AVIF’s official syntax lives in the AV1 Image File Format specification.