KB vs MB: Understanding Image File Size
What KB and MB mean, how to convert between them, and why upload forms often ask for sizes in KB.
File sizes are measured in bytes. A kilobyte (KB) is roughly a thousand bytes, and a megabyte (MB) is roughly a thousand kilobytes. Computers usually count in powers of two, so many programs treat 1 MB as 1024 KB, and that is how this site's tools count too. A few systems count 1 MB as 1000 KB, so a number can differ slightly between programs.
Quick conversion table
| In KB | In MB (approx.) |
|---|---|
| 20 KB | 0.02 MB |
| 50 KB | 0.05 MB |
| 100 KB | 0.1 MB |
| 200 KB | 0.2 MB |
| 500 KB | 0.5 MB |
| 1024 KB | 1 MB |
| 2048 KB | 2 MB |
Why forms use KB limits
Websites that collect many uploads set limits to save storage and keep pages fast. Photo and signature fields often have small limits, while document fields allow more. If your file is too big, it will usually be rejected with a size error.
What decides file size
Three things matter most: how many pixels the image has, how much compression is applied, and the format. A large photo saved at high quality can be several MB, while the same photo resized and compressed can be under 100 KB.
Get to your size
Choose the limit you need: 20 KB, 50 KB, 100 KB, 1 MB, or open the main compress tool and type any size.