Where the 20KB limit comes from
Few numbers in the life of an internet user are as stubborn as the 20KB upload cap. Old-school forums built on phpBB, vBulletin, and similar software have enforced tiny avatar limits for decades, partly out of tradition and partly because thousands of avatars load on every thread page. Favicons live under the same roof: browsers request that little icon on every single page view, so keeping it featherweight is just good manners. Chat stickers, email signature logos, and the thumbnail images inside comment systems all share the same constraint — the picture will be displayed at somewhere between 16 and 150 pixels wide, so there is simply no reason to ship more bytes than the eye can use.
The good news: 20KB is plenty for anything displayed that small. A 150-pixel avatar compressed as WebP or JPEG can look crisp at a fraction of that budget — the trick is starting from the right crop.
Shrinking a photo to 20KB without turning it to mush
Upload a full 12-megapixel vacation photo and ask any tool to squeeze it under 20KB, and the result will look like a watercolor left in the rain. The smarter path is to crop first, mentally if not literally: avatars and favicons are almost always square, and the subject is almost always a face or a simple logo. Crop tight around the face, eyes in the upper third, and you give the compressor far fewer background pixels to waste bytes on.
The compressor then does the heavy lifting automatically. It binary-searches JPEG or WebP quality from 90% down to 10% to find the highest quality that fits under 20KB, and only if the file is still too big does it gently shrink the dimensions — never below 320 pixels on the short side, which is still more than double what most avatar slots display. Because everything runs in your browser, you can retry with a tighter crop as often as you like — nothing is ever uploaded.
Picking the right format for tiny images
For photographic avatars — faces, pets, snapshots — WebP usually produces the smallest file at a given quality, with JPEG as the universal fallback that every forum on earth accepts. For flat graphics like favicons, logos, and chat stickers with solid colors and sharp edges, PNG is often dramatically smaller than JPEG, because lossless compression loves flat color. If your source is a tiny icon, try PNG first; if it is a photo of you, try WebP or JPEG. The format selector above lets you switch in one click and compare the results side by side before you download.