30 KB
Resize a photo to exactly 30 KB
30 KB is 30,720 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. 30 KB is most often asked for on signature fields and small photo boxes.
Updated , written and tested by Rizwan Aslam
Resize your photo to 30 KB
Preset to 30 KB. Change the number if your form asks for something else.
What 30 KB actually looks like
Thirty kilobytes usually appears as the upper end of a signature range rather than as a standalone limit. If your form says something like 10 KB to 30 KB, this is the ceiling and not the goal. Landing near 25 KB keeps you clear of both edges, which matters because the too small error message is often worded identically to the too large one.
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 30 KB gives you at three sizes.
| Dimensions | Pixels | Bits per pixel | Result |
|---|---|---|---|
| 300 x 400 | 0.12 MP | 2.05 | Excellent, no visible difference |
| 600 x 800 | 0.48 MP | 0.51 | Visible artifacts around text and edges |
| 1200 x 1600 | 1.92 MP | 0.13 | Heavy artifacts, clearly degraded |
The largest photo that still looks very good at 30 KB is around 480 by 640 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 30 KB | Binary searches encoder quality downward until it fits, then pads back up to the exact byte | As good as 30 KB allows |
| Under 30 KB | Raises encoder quality as high as still fits, then pads the remainder losslessly | Slightly sharper than before |
| Already 30 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 30 KB accepted
Three things worth knowing before you upload.
- Keep signatures on white. A clean white background compresses to almost nothing, so all the bytes go to the ink.
- 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.
More rejection messages and what each one really means are in the guide to why forms reject photos.
Questions about the 30 KB target
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 30 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.
Should I use JPG or PNG at this size?
JPG, unless the form insists otherwise. PNG stores everything losslessly, so a PNG at 30 KB means shrinking the picture drastically to fit. JPG gets you far more picture for the same bytes.
How many bytes is 30 KB exactly?
30,720 bytes if the system treats 1 KB as 1024 bytes, or 30,000 if it uses 1000. Forms rarely say which. Because 30 KB is usually a maximum, aim at the smaller reading and you clear both.