File Size Converter
Convert between bytes, kilobytes, megabytes, gigabytes, terabytes and petabytes instantly. Supports both SI (base 1000) and binary (base 1024) systems.
🔄 Conversion Tools
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Binary vs SI — What's the Difference?
The two base systems can cause significant confusion. In the binary (IEC) system used by most operating systems, 1 KB = 1,024 bytes. In the SI (decimal) system used by hard drive manufacturers and many standards bodies, 1 KB = 1,000 bytes. A 1 TB hard drive contains 1,000,000,000,000 bytes — but your OS reports it as only ~931 GiB.
Unit Reference Table
| Unit | Binary (bytes) | SI (bytes) |
|---|---|---|
| 1 KB | 1,024 | 1,000 |
| 1 MB | 1,048,576 | 1,000,000 |
| 1 GB | 1,073,741,824 | 1,000,000,000 |
| 1 TB | 1,099,511,627,776 | 1,000,000,000,000 |
| 1 PB | 1,125,899,906,842,624 | 1,000,000,000,000,000 |
When to Use Each
Use binary when working with RAM, OS file sizes or programming. Use SI when comparing with storage device specs, network bandwidth or cloud storage billing, which typically advertise in decimal units.