Data Size Converter
Convert bits, bytes and every prefix - and see the decimal (1000) and binary (1024) answers side by side.
| Scale | Decimal (x1000) | Binary (x1024) |
|---|---|---|
| Bits | - | |
| Bytes | - | |
| Kilo | - | - |
| Mega | - | - |
| Giga | - | - |
| Tera | - | - |
Left column uses powers of 1000 (what drive makers and networks quote). Right column uses powers of 1024 (what your operating system and RAM use).
Two ways to count the same bytes
A byte is a byte, but the prefixes on top of it come in two flavours. The decimal (SI) system multiplies by 1,000 at each step: 1 kB = 1,000 bytes, 1 MB = 1,000 kB, and so on. The binary (IEC) system multiplies by 1,024, because computers count in powers of two: 1 KiB = 1,024 bytes, 1 MiB = 1,024 KiB. The proper binary units are spelled kibi, mebi, gibi and tebi (KiB, MiB, GiB, TiB) to keep them distinct.
Why "500 GB" shows as 465 GiB
This is the number one source of confusion. A drive labelled 500 GB holds exactly 500,000,000,000 bytes - the manufacturer uses the decimal definition, so the maths is clean. Your operating system, though, divides by 1,024 three times to reach the giga level: 500,000,000,000 / 1,024 / 1,024 / 1,024 = 465.66. So it reports 465 GiB (often still mislabelled "GB"). Nothing is lost; the drive is honest. The two systems simply disagree by about 7.4 percent at the giga level, and the gap widens the higher you go - a 1 TB drive shows as roughly 931 GiB.
Bits versus bytes
Storage is measured in bytes (capital B); data-transfer speed is measured in bits (lower-case b). There are 8 bits in a byte, so a 100 Mbps connection tops out near 12.5 MB per second. Confusing the two makes downloads look eight times slower than advertised. If you are working out how long a file will take to download, keep an eye on that factor of eight.
Working with raw numbers elsewhere? The binary converter turns decimal into base-2, and the all-in-one unit converter covers length, weight and more alongside data. For plain arithmetic, the percentage calculator is handy when you want the exact gap between GB and GiB.