Compress an image to 100 KB
Drop in a photo and it comes back under 100 KB. There is no quality slider to guess at — the tool tries a range of quality settings, keeps the best one that still fits the limit, and tells you the size it landed on.
Everything happens inside this browser tab. Your image is not uploaded to a server and is not stored anywhere — close the tab and it is gone.
How the 100 KB target is reached
The tool re-encodes your image several times at different quality levels, halving the range each round the way you would guess a number between one and a hundred. After about seven attempts it has found the highest quality whose output still fits under 100 KB, and that is the file you get. If even the lowest quality setting cannot get there — which happens with very large photographs — it reduces the pixel dimensions by 20% and searches again, repeating until the file fits. The result line shows the size it actually achieved, so you never have to check in a file manager.
Questions about the 100 KB limit
Why do forms insist on under 100 KB?
The limit is almost always inherited rather than chosen. Government portals, university applications, job boards and exam registration systems were built when storage and bandwidth were expensive, and the upload cap written into them then has never been revisited. Multiplied by millions of applicants it is still a real saving on their side, which is why nobody raises it. The number is a hard check on the server: 100 KB passes, 101 KB is rejected with no explanation.
How much quality do I lose getting down to 100 KB?
It depends entirely on how big the image started. A passport-style headshot around 600×800 pixels reaches 100 KB at high quality and looks untouched. A modern phone photo at 12 megapixels has to shed about 98% of its bytes, so expect visible softening and some blockiness in the background — recognisable and perfectly acceptable for a form, but not something to print. Cropping to just the part that matters before you compress buys back a lot of quality.
What if my image cannot reach 100 KB?
Then the tool starts shrinking the dimensions in 20% steps and tries again, because past a certain point there is simply no way to describe that many pixels in that few bytes. You will see this as an output that is smaller on screen as well as smaller on disk. In the rare case it runs out of room entirely, the result line says so and gives you the smallest file it managed, rather than pretending it succeeded.
Does the file have to be exactly 100 KB?
No, and it should not be. Upload forms check for "at most", so anything from 1 KB to 100 KB passes. The tool aims to land just under the line because that is where the quality is highest — a file that comes back at 97 KB has used the budget well. If you are pasting the size into a field somewhere, use the number shown on the result line.
Is 100 KB measured in kilobytes or kibibytes?
This page treats 100 KB as 102,400 bytes, the same convention Windows and most upload validators use. If a form is unusually strict and counts 100,000 bytes instead, a file reported here as 99 KB could still be refused. If that happens, use the 50 KB preset — the extra headroom removes any doubt.