10 KB
Resize a photo to exactly 10 KB
10 KB is 10,240 bytes. This page is preset to that number, and the tool lands on it exactly whether your file needs to shrink or grow. Everything runs in your browser, so your photo is never uploaded. 10 KB is most often asked for on thumbnail fields and very small signature boxes.
Updated , written and tested by Rizwan Aslam
Resize your photo to 10 KB
Preset to 10 KB. Change the number if your form asks for something else.
What 10 KB actually looks like
Ten kilobytes is the smallest number forms realistically ask for, and it is almost always meant for a signature rather than a face. A signature is ink on white paper, which compresses to almost nothing, so 10 KB is generous for a signature and brutal for a photograph. If a portal asks for a photo at 10 KB, read the field label again before you assume it means your face.
This is a small target. Almost every photo arriving here has to shrink, often by a very large factor, so the pixel dimensions matter more than they do anywhere else. The measure that decides this is bits per pixel: the file size in bits divided by the number of pixels. Here is what 10 KB gives you at three sizes.
| Dimensions | Pixels | Bits per pixel | Result |
|---|---|---|---|
| 300 x 400 | 0.12 MP | 0.68 | Acceptable, slightly soft up close |
| 600 x 800 | 0.48 MP | 0.17 | Heavy artifacts, clearly degraded |
| 1200 x 1600 | 1.92 MP | 0.04 | Heavy artifacts, clearly degraded |
The largest photo that still looks very good at 10 KB is around 280 by 370 pixels. That is the point where this target still delivers roughly 0.8 bits per pixel. Above it, quality starts dropping whatever tool you use.
Both directions, one page
At a target this small the shrink case is almost the only one that happens, but the grow case still matters for signature scans that came out unusually light. Most sites give you one tool to grow a file and a different one to shrink it, but the same algorithm does both, so this page does both.
| Your file | What the tool does | Picture quality |
|---|---|---|
| Over 10 KB | Binary searches encoder quality downward until it fits, then pads back up to the exact byte | As good as 10 KB allows |
| Under 10 KB | Raises encoder quality as high as still fits, then pads the remainder losslessly | Slightly sharper than before |
| Already 10 KB | Nothing at all, and it tells you so | Untouched |
The padding is not a trick. Every major format reserves a block for data decoders skip, so writing neutral bytes there changes the file size and not one pixel.
Getting 10 KB accepted
Three things worth knowing before you upload.
- Check for a minimum. Small targets are usually written as a range, and compressing as hard as possible drops you under the floor.
- Shrink the dimensions first. At this size the pixel count is what decides whether the result is readable.
- Keep signatures on white. A clean white background compresses to almost nothing, so all the bytes go to the ink.
More rejection messages and what each one really means are in the guide to why forms reject photos.
Questions about the 10 KB target
How many bytes is 10 KB exactly?
10,240 bytes if the system treats 1 KB as 1024 bytes, or 10,000 if it uses 1000. Forms rarely say which. Because 10 KB is usually a maximum, aim at the smaller reading and you clear both.
Can a photo really work at 10 KB?
Only at small pixel dimensions. At 300 by 400 the result is 0.68 bits per pixel, which reads as acceptable, slightly soft up close. At 1200 by 1600 the same 10 KB gives 0.04 bits per pixel and the picture falls apart. Resize first.
The form says my file is too small. What now?
That means there is a minimum as well as a maximum. Compressing as hard as possible pushed you under it. Pick a number inside the range rather than the smallest possible file and run it again.
Is 10 KB enough for a signature?
Usually yes, and more comfortably than for a photo. A signature is ink on white, so most of the image compresses to almost nothing and the bytes go where the detail actually is.