Why a form says the file is too small
Many upload forms set a minimum as well as a maximum, for example "between 10 KB and 20 KB" for a signature or "20 KB to 50 KB" for a photograph. A minimum is meant to stop blank, tiny or badly scanned images. A clean signature on white paper, or a photo that has already been compressed hard, can fall below it, and the form refuses it even though the picture is fine.
How to increase image size in KB honestly
There are two honest ways to make an image file bigger, and this page uses them in this order:
- Higher quality. The image is saved again as a JPG at a higher quality setting. This keeps more fine detail and gradation, and the file grows. Often that alone is enough to pass a 10 or 20 KB minimum.
- More pixels. If the highest quality is still under the minimum, the picture is enlarged in small steps, up to four times its width and height and never past 4,000 pixels on the longest side, until it reaches the minimum.
The page stops just above the number you set, so a range like 10 to 20 KB is met by typing 10. What it never does is append filler bytes to the end of the file. That trick changes the size, but it leaves junk inside the file that a strict upload check or image program may reject.
If the minimum cannot be reached
A very small image, for example a 100 x 40 pixel signature, may not reach a large minimum even after both steps. The page then says so and shows the largest honest result. The fix is a better original: photograph the signature or document again at full camera resolution and crop it, then bring it down to the range with reduce image size in KB or up with this page.
Keep the pixel size the form asks for
If the form fixes the width and height as well, open Width and height, type them and choose Exactly this size. The page will then only raise the quality, never the pixel count. With Fit inside, the numbers you type are the largest size the picture may grow to.
Typical cases
- Signature under 10 KB: set 10 KB here. A tightly cropped signature usually reaches it at a higher quality alone.
- Photo under 20 KB after another tool: start from the original photo instead of the over-compressed copy if you still have it, and use compress image to 50 KB or 20 KB, which land just under the maximum.
Like every DocFig image tool, this runs in your browser and the image never leaves your device.
The image is redrawn with your browser's own canvas, so the result depends on the browser's JPG, PNG and WebP encoders. MDN's image file type guide explains which format suits photos, signatures and scans.