Eight image formats explained

JPG — built for photographs

Published in 1992 by the Joint Photographic Experts Group, which is where the name comes from. It compresses photographs aggressively by discarding detail the eye is less sensitive to, and it has no transparency. Thirty years on it is still the most compatible image format in existence.

Reach for it when: photos, product shots, anything that has to be sent to someone.

PNG — built for lossless and transparency

Created in 1996 partly to sidestep the GIF patent of the era. Its compression is lossless — the image never degrades — and it carries a full alpha channel. The cost is size, especially for photographic content.

Reach for it when: screenshots, logos, transparent assets, anything you will edit again.

GIF — the oldest survivor

1987, older than the web. It supports 256 colours per frame and rudimentary animation, and it has one advantage nothing else matches: absolutely everything opens it, including software from decades ago.

Reach for it when: chat reactions, short loops. For anything else, animated WebP is a fraction of the size.

BMP — the plainest format

The original Windows bitmap, essentially uncompressed: every pixel stored as-is. Quality is perfect; so is the file size — a 1920×1080 BMP runs about 6 MB.

Reach for it when: legacy software, industrial equipment, scanning workflows. Almost never on the web.

SVG — a drawing, described in code

Not a bitmap at all, but XML describing shapes: "a circle of radius 40 at (50,50)". Infinitely scalable, usually a few kilobytes, and editable in a text editor.

Reach for it when: icons, logos, illustrations, charts, maps.

WebP — built for the web

Google released it in 2010 with one goal: smaller web images. 25–35% smaller than JPG at the same visual quality, dramatically smaller than PNG, with transparency and animation supported. Every current browser reads it.

The weakness is software support — some older desktop applications still cannot open it. That is why WebP to JPG remains a common request.

Reach for it when: any image on a website or in an app.

AVIF — the current compression champion

Built on the AV1 video codec and released in 2019. Another 20–50% smaller than WebP at matching quality, with transparency and HDR. The trade-offs are slow encoding and patchy support on older devices.

Reach for it when: you are chasing every byte and can serve a fallback to older browsers.

ICO — the icon container

The Windows icon format, and its defining feature is that one file holds several sizes. A browser tab reads the 16×16 frame while a desktop shortcut reads the 256×256 one. It is what favicons are made of — see the favicon guide.

Lookup table

To move between any of them, use the conversion tools — local, private, no uploads.