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AVIF, WebP or JPEG XL.

All three weigh less than JPEG, but not by the same amount, nor everywhere. We measured them at the same perceived quality.

−41%JPEG XL vs JPEG, without it showing even up close

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How we measured

Comparing formats “at quality 80” is meaningless: AVIF's 80 isn't JPEG's 80. The fair way is to match what you see. For that we use SSIMULACRA 2, a perceived-quality metric: at 80 you can't tell the image apart from the original side by side, and at 90 not even up close.

For each photo and each format, Apolo finds the lowest quality that reaches that score, and we compare the sizes.

If you can't tell side by side (score 80)

  • AVIF62 KB · −25 % vs JPEG
  • JPEG XL66 KB · −20 % vs JPEG
  • WebP78 KB · −6 % vs JPEG
  • JPEG83 KB
The 24 photos of the Kodak Lossless True Color Image Suite (768×512, PNG of 626 KB on average), each at the lowest quality that reaches a SSIMULACRA 2 score of 80. Measured with apolo 0.18.3, on October 27, 2026.

If you can't tell even up close (score 90)

At high quality, JPEG XL pulls ahead (41% less than JPEG) with AVIF close behind (36%). At tighter quality, AVIF is the lightest (25%). WebP sits in between, and its advantage grows with quality.

  • JPEG XL134 KB · −41 % vs JPEG
  • AVIF146 KB · −36 % vs JPEG
  • WebP174 KB · −23 % vs JPEG
  • JPEG226 KB
The 24 photos of the Kodak Lossless True Color Image Suite (768×512, PNG of 626 KB on average), each at the lowest quality that reaches a SSIMULACRA 2 score of 90. Measured with apolo 0.18.3, on October 27, 2026.

Where each one opens

WebP

In every current browser and almost any app. The safest.

AVIF

In current browsers (Chrome, Edge, Firefox, and Safari for years now) and in more and more apps.

JPEG XL

Safari opens it; other browsers are getting there. Before serving it alone, check caniuse.com.

JPEG

Everywhere, including email, printers and old software.

Which to choose

For a website

AVIF, with WebP or JPEG as a fallback in a <picture> for whatever can't open it.

To share without thinking

WebP, or JPEG if it goes somewhere old.

To archive at high quality

JPEG XL. It also recompresses the JPEGs you already have without losing anything.

Screenshots, logos and graphics

Lossless WebP or optimized PNG.

Optimize images for the web →Compress without losing quality →

Try it with your photos

The same, with your images: Apolo converts to all four formats and keeps the lightest for each photo.

apolo lote photos/ --formato avif,jxl,webp,jpeg --objetivo 80 --mas-ligero

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