The best image formats for email newsletters
Why most email clients still don't speak WebP, and what that means for your campaign open-graph images.
Picking an image format used to be simple: JPG for photos, PNG for screenshots, done.In 2026 that mental model leaves real bandwidth — and real performance — on the table. This article walks through the three formats you'll actually ship in production this year.
The contenders
Modern browsers support three serious lossy formats: JPEG, WebP, and AVIF. PNG is still around for true lossless work but rarely wins the file-size fight for photographic content.
- JPEG — universal, ~30 years old, baseline.
- WebP — Google, ~25–30% smaller than JPEG at equal quality, supported everywhere except very old iOS.
- AVIF — newer, ~30% smaller than WebP at equal quality, slower to encode, supported in all evergreen browsers.
The numbers (12-image test set)
We took a set of twelve real-world images — product photos, hero illustrations, screenshots — and re-encoded each at quality 78. Here's the average:
format │ size │ vs JPEG ──────────┼──────────┼──────── JPEG │ 312 KB │ — WebP │ 224 KB │ −28% AVIF │ 154 KB │ −51%
Quality-perception note
At quality 78 all three formats are visually indistinguishable for typical photographic content on a 2x display. Below 60, WebP and AVIF hold up significantly better than JPEG, where blocky 8×8 DCT artifacts become visible.
The fastest image is the one your visitor never has to download.
What we recommend
- Use AVIF as the primary format with a WebP fallback inside
<picture>. - Keep a JPEG source-of-truth — old email clients still need it.
- Compress at quality 76–80. Below 70, you're trading visible quality for bytes that don't matter.
You can do all of this without leaving your browser — drop a file into our compressor, pick AVIF, and ship. No upload, no roundtrip, no signup.