Compress image to 20KB
20 KB is one of the strictest limits out there — signature images, passport-photo uploads and some exam portals demand it. This tool scales and compresses automatically until your image fits.
100% private: files are processed in your browser and never uploaded to any server.
How it works
- Drop your image into the box — the 20 KB target is already set.
- The tool lowers quality first, then dimensions, until the file is under 20 KB.
- Download the result and check the final size next to the file.
Where a 20 KB limit comes from
Twenty kilobytes is not a size anyone would choose for a photograph. It survives because of a specific kind of form: government portals, university and competitive-exam registrations, and older banking systems, many of which were specified when storage was budgeted per record and never revisited. The instruction usually arrives as a line in a PDF — "photograph: JPEG, 20 KB maximum; signature: JPEG, 10 KB maximum" — with no guidance on how to get there.
Knowing that the limit was written for a scanned signature or a small identity photograph, rather than for a modern phone snapshot, tells you how to approach it. You are not trying to preserve a four-thousand-pixel image inside 20 KB. You are producing the small, plain image the form was designed around.
What genuinely fits in 20 KB
As a working guide, expect the result to land somewhere around 400 × 400 pixels for a photograph, and to look perfectly acceptable at the size these forms display it. Simple, high-contrast subjects do best: a signature on white, a stamp, a head-and-shoulders portrait against a plain background. Those are exactly the images with large flat areas that compress efficiently.
Detailed scenes are the ones that suffer. A full-body photo taken outdoors, a group shot, anything with foliage or patterned clothing carries high-frequency detail across the whole frame, and at 20 KB there is simply not enough budget to describe it. If your result looks mushy, the honest reading is that the source image is too busy for the target — crop tighter around the subject and try again. Cropping removes pixels you were paying for and lets the remaining ones keep more quality.
Getting it accepted first time
Aim a little below the limit rather than exactly at it. File managers round sizes for display, so something shown as "20 KB" may be 20,900 bytes and still be rejected by a validator that counts strictly. A result at 18 or 19 KB removes that entire class of problem.
Check the other constraints too, because these forms rarely impose only one. Minimum and maximum pixel dimensions, an accepted format list that often excludes PNG, and sometimes a required aspect ratio all appear alongside the size cap. Use JPEG here unless the form explicitly asks otherwise: PNG is lossless and will almost never fit into 20 KB unless the image is tiny or has very few colours.
Good to know
20 KB is one of the strictest limits in use, and it exists for a specific reason: signature images and small ID photos on government and exam-registration portals. It is not a realistic target for a normal photograph at full resolution.
Expect the image to end up around 400 × 400 pixels. For a signature, a stamp or a thumbnail that is perfectly usable — those are simple, high-contrast images that survive heavy compression well. For a detailed portrait, 20 KB will visibly cost you.
Use JPG here. PNG is lossless and almost never fits in 20 KB unless the image is tiny or has very few colours, so if the portal accepts JPG that is the format to give it.
Frequently asked questions
Can any image really fit in 20 KB?
Yes, but at this size the image must be small — think 300–600px. The tool reduces dimensions as much as needed; for a signature or a thumbnail the result stays perfectly usable.
Who asks for images under 20 KB?
Government and exam-registration portals (especially for signature and photo uploads), some job boards and legacy systems with tight storage rules.
Which format works best at 20 KB?
JPG, by far. PNG is lossless and rarely fits in 20 KB unless the image is tiny or has very few colors.
Is my document photo uploaded anywhere?
No — compression runs inside your browser, which matters when the image is an ID photo or a signature. It never leaves your device.
The form asks for a signature between 10 and 20 KB. How do I hit a range?
Set the target to the top of the range, 20 KB, and check the resulting size shown next to the file. Signature images are high-contrast line art on white, so they compress very efficiently and usually land comfortably inside the window on the first try.
Can I use a PNG for a 20 KB signature?
Sometimes, and it is worth trying: a signature is flat black on white with very few colours, which is the one case where PNG compresses extremely well. If it does not fit, convert it to JPG and compress that instead.
Will the photo still be recognisable at 20 KB?
For a head-and-shoulders portrait, yes — that is the kind of image the limit was designed for. For a detailed full-body or group photo, expect visible quality loss, and crop to the face before compressing.