How to reduce image size in KB
- Tap Choose a photo and pick your image.
- Type the limit your form gave you, in kilobytes.
- Tap Reduce size and read the result.
- Save the file, or try a different number without starting over.
Kilobytes are not a setting a camera has
Nothing about a photograph is measured in kilobytes until it has been encoded. The size of the file depends on how many pixels there are, how much fine detail is in them, and how hard the encoder was told to squeeze — so "make this 40 KB" is a question with no single answer, and every tool that claims one is searching for it the same way this page does.
What this page does is try, measure, and try again: it encodes your image at a range of quality settings, keeps the largest result that still fits under your number, and reduces the pixel size only when quality alone cannot get there. Then it tells you what it landed on, which is the part most tools leave out.
Choosing a number when the form was vague
If the instruction said "under 1 MB", use 1000. If it gave a range like 20 to 50 KB, aim at the top of it — a file at 22 KB and a file at 48 KB both pass, and the larger one looks better. If it named no number at all, 200 KB is a sensible default that almost nothing rejects.
The strict reading of KB is used throughout: 50 KB means 50,000 bytes, not 51,200. A form using the other convention accepts the stricter file too, so there is no case where this costs you.