Binary (base 1024)
| Unit | Value |
|---|
Decimal (base 1000)
| Unit | Value |
|---|
How to use the File Size Converter
- Enter the file size value in the Value field.
- Select the unit from the dropdown, binary units (KiB, MiB) or decimal units (KB, MB).
- Both conversion tables update instantly with all equivalent values.
Binary vs decimal file sizes
Binary units (kibibyte, mebibyte, gibibyte...) are powers of 1024. Operating systems use them to report file sizes, RAM capacity, and disk usage. The IEC standard names them KiB, MiB, GiB, TiB.
Decimal units (kilobyte, megabyte, gigabyte...) are powers of 1000. Hard drive and SSD manufacturers use them to describe storage capacity. The SI standard names them KB, MB, GB, TB.
This is why a "500 GB" hard drive shows up as about 465 GiB in Windows or macOS, the OS uses binary units while the manufacturer used decimal.
Quick reference table
| Binary | = Bytes | Decimal | = Bytes |
|---|---|---|---|
| 1 KiB | 1,024 | 1 KB | 1,000 |
| 1 MiB | 1,048,576 | 1 MB | 1,000,000 |
| 1 GiB | 1,073,741,824 | 1 GB | 1,000,000,000 |
| 1 TiB | 1,099,511,627,776 | 1 TB | 1,000,000,000,000 |
When does this matter?
- Buying storage: a 1 TB SSD has 1,000 GB decimal but only 931 GiB binary; that is why it shows less in Windows
- Network speeds: internet providers advertise speeds in megabits per second (Mbps); to download a 1 GB file takes longer than you might expect because 1 GB = 8,000 Mb, and Mbps / 8 = MB/s
- RAM: memory modules are always binary; 8 GB RAM = exactly 8 GiB = 8,589,934,592 bytes
- File transfers and budgets: knowing exact byte counts matters when staying within cloud storage quotas or upload limits