File Size Converter 🔒 Your data never leaves your browser.
Convert bytes, KB, MB, GB and TB — with a binary/decimal toggle.
| Unit | Value | |
|---|---|---|
| Bytes | ||
| Kilobytes (KB) | ||
| Megabytes (MB) | ||
| Gigabytes (GB) | ||
| Terabytes (TB) | ||
| Petabytes (PB) |
About this tool
A "kilobyte" has meant two different things for decades, and both are still in daily use. The decimal (SI) convention treats 1 KB as exactly 1000 bytes, 1 MB as 1000 KB, and so on — this is what hard drive manufacturers print on the box, and what macOS and most modern Linux tools display. The older binary convention treats 1 KB as 1024 bytes (2¹⁰), 1 MB as 1024 KB, and so on — this is what Windows File Explorer, many older utilities, and RAM specifications still use, even though the technically correct binary label is KiB/MiB/GiB rather than KB/MB/GB.
That 2.4% gap per step (1024 vs 1000) compounds fast: at the terabyte scale it is roughly a 10% difference, which is exactly why a drive labelled "1 TB" shows up as about 931 GiB in Windows. This converter lets you pick either convention with one toggle, so you can match whichever system produced the number you are checking against, and see the same value expressed in every unit from bytes to petabytes at once.
Frequently asked questions
Why does my OS show a different file size than this converter with the same numbers?
This is almost always the binary-vs-decimal mismatch: Windows File Explorer traditionally reports "KB/MB/GB" using 1024-byte multiples, while macOS Finder and most drive manufacturers use 1000-byte (decimal, SI) multiples for the same labels. Toggle this tool's binary/decimal option to match whichever system produced the number you're comparing against.