Who asks for 20 KB
Almost always a government or examination portal. Indian recruitment and university systems are the most common source — UPSC, SSC, state boards and university admission forms routinely cap a photograph at 20 KB and a signature at 10 KB. Some legacy HR systems still do the same.
What fits in 20 KB
Roughly a 400 × 500 headshot at moderate quality, or a 600 × 400 image if the subject is simple. A plain background helps enormously; a busy scene at this size will visibly break up.
What it costs you
A great deal. At 20 KB you will see blocking around edges and flat patches in skin tones and sky. That is the format working as intended — it is not a fault in the file. If the portal accepts a smaller pixel size, reducing dimensions first gives a better-looking result than forcing a large image down to 20 KB.
How this hits the number
Compression quality and file size do not move together in a straight line, so there is no setting that reliably produces 20 KB. This encodes your image repeatedly at different quality levels, narrowing in on the highest one whose output still fits, and returns that file. It never hands back something over the limit, because a file over the limit is the one thing you cannot use.
All of it runs in this browser tab using the canvas API. Your image is read from disk into the page, worked on, and written back out. Nothing is uploaded, which you can confirm yourself — open your browser's network tab and watch it stay empty while the tool runs.
Common questions
How do I compress a photo to 20 KB for an exam form?
Set the limit to 20 KB and drop the photo in. This searches for the highest JPEG quality that still lands under 20,480 bytes and hands that back. If the form also caps the pixel dimensions — many specify 200 × 230 or similar — resize to those dimensions first, because a smaller image spends its 20 KB on far fewer pixels and looks considerably better.
Why does my photo look blocky at 20 KB?
Because 20 KB is very little data for a photograph. JPEG discards detail in blocks of eight pixels, and at this size it must discard a lot of them. Edges gain halos and smooth areas such as skin and sky turn patchy. A photo taken against a plain wall compresses much better than one taken outdoors.
Is 20 KB the same as 20 KB on the form?
Usually yes, but check. Most portals mean 20,480 bytes — 20 × 1024, which is what this uses. A few mean 20,000 bytes exactly. If your file is accepted by this tool and rejected by the form, that 480-byte difference is the likely reason; set the limit to 19 KB and try again.