KB vs MB: how upload size limits are counted
Updated 23 October 2026 · Zenvoq Labs
| Limit | Binary (1024) | Decimal (1000) |
|---|---|---|
| 20KB | 20,480 bytes | 20,000 bytes |
| 100KB | 102,400 bytes | 100,000 bytes |
| 300KB | 307,200 bytes | 300,000 bytes |
| 1MB | 1,048,576 bytes | 1,000,000 bytes |
Why the difference exists
Computers count in powers of two, so 1KB was historically 1,024 bytes. Storage makers and some software use the decimal 1,000. Strictly, 1,024 bytes is a kibibyte (KiB), but nearly every form still writes it as KB.
Picking a safe target
If a form says 300KB, target 280KB. If it says 20KB, target 19KB. You lose almost no quality and avoid being rejected by whichever way the portal counts. Also check the minimum — many exams reject files that are too small.
Frequently asked questions
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