Binary Prefixes
SI Prefixes are not used in the computer world, things are a bit different:
Commonly used
These prefixes are easily confused with SI Prefixes.
| Symbol | Prefix | Factor | Factor |
|---|---|---|---|
| P | peta | 250 | 1125899906842624 |
| T | tera | 240 | 1099511627776 |
| G | giga | 230 | 1073741824 |
| M | Mega | 220 | 1048576 |
| k | kilo | 210 | 1024 |
IEC 60027-2 / IEEE 1541-2002
IEC has adopted these prefixes to solve the confusion. These are not widely used (yet).
| Symbol | Prefix | Factor | Factor |
|---|---|---|---|
| Yi | yobi | 280 | 1208925819614629174706176 |
| Zi | zebi | 270 | 1180591620717411303424 |
| Ei | exbi | 260 | 1152921504606846976 |
| Pi | pebi | 250 | 1125899906842624 |
| Ti | tebi | 240 | 1099511627776 |
| Gi | gibi | 230 | 1073741824 |
| Mi | mebi | 220 | 1048576 |
| Ki | kibi | 210 | 1024 |
kibi originates from kilobinary
Bits/Bytes
| Symbol | Suffix | Description |
|---|---|---|
| b | bit | one binary digit, value 0 or 1 |
| B | Byte | 4-10 bits, but in most cases 8 bits |
| o | octet | 8 bits |
Examples
| Symbol | Prefix |
|---|---|
| 1 kB | 1024 bytes (but 1000 bytes according to SI) |
| 1 KiB | 1024 bytes (IEC) |
| 10 Mb/s | 10485760 bits/second = 1310720 bytes/second (but 1250000 bytes/seconds according to SI) |
| 10 Mib/s | 10485760 bits/second = 1310720 bytes/second (IEC) |
Standards
- IEC 60027-2:2005
- IEEE 1541-2002