Why file size matters for uploads
Forms cap file size to control storage and bandwidth, and they enforce the cap strictly — one kilobyte over and the upload fails. Some portals also set a minimum, so the goal is to land inside a window, not just under a ceiling.
KB vs MB, and JPEG vs PNG vs WebP
1 MB is 1024 KB, so a 1 MB cap is far more generous than a 100 KB one. Format matters just as much as the number: JPEG compresses photos efficiently and is the safest choice for strict KB targets; PNG is lossless and usually stays too large; WebP is the smallest of the three but only works where the destination accepts it.
- JPEG — best default for photos and tight KB caps.
- PNG — keep only when you need transparency or pixel-perfect graphics.
- WebP — smallest files at the same quality, when supported.
How to hit an exact KB target
Two levers control file size: compression quality and pixel dimensions. For a small target like 20–50 KB, lowering quality alone is rarely enough, so reduce the dimensions too. For a roomy target like 1 MB, you can usually keep full resolution and high quality. A tool that targets a KB value adjusts both for you.
Common targets and when to use them
Different uploads ask for different sizes. These pages pre-set the target and walk you through it:
- 10–25 KB — signatures and very strict exam uploads
- 50–100 KB — exam photos and most government forms
- 150–300 KB — job portals and document scans
- 500 KB – 1 MB — roomier portals and email attachments
Tips to keep quality high
Always start from the highest-quality original you have — re-compressing an already-compressed file stacks artefacts. Crop tightly so the compressor spends its budget on the subject, and target slightly under the limit so a strict check still accepts the file.