Mining capability is measured in the number of attempts to find a block a miner can perform. Each attempt consists of creating a unique block candidate, and creating a digest of the block candidate by means of the
SHA-256d, a cryptographic hashing function. Or, in short, a hash. Since this is a continuous effort, we speak of hashes per second or [H/s].
Hash rate denominations
- 1 kH/s is 1,000 (one thousand) hashes per second
- 1 MH/s is 1,000,000 (one million) hashes per second.
- 1 GH/s is 1,000,000,000 (one billion) hashes per second.
- 1 TH/s is 1,000,000,000,000 (one trillion) hashes per second.
- 1 PH/s is 1,000,000,000,000,000 (one quadrillion) hashes per second.
- 1 EH/s is 1,000,000,000,000,000,000 (one quintillion) hashes per second.
- 1 ZH/s is 1,000,000,000,000,000,000,000 (one sextillion) hashes per second.
- 1 MH/s = 1,000 kH/s
- 1 GH/s = 1,000 MH/s = 1,000,000 kH/s
- 1 TH/s = 1,000 GH/s = 1,000,000 MH/s = 1,000,000,000 kH/s
- and so forth
SI unit prefixes
The denomination of hash rates follows the International System of Units (SI). Hereby, the prefixes kilo, mega, giga, tera, peta, exa, and zetta each translate to an increase by a factor of one thousand.
Please note, that the symbol for kilo is a lower-case "k". As "K" is the symbol for
kelvin, the unit of thermodynamic temperature.
The following table from Wikipedia shows an overview of the prefixes, symbols, and factors they correspond to.
Inconsistency of kilobyte, megabyte, and gigabyte
The computer industry's use of kilobyte, megabyte, and gigabyte is inconsistent with the SI. The Joint Electron Device Engineering Council (JEDEC) has redefined the prefixes kilo, mega and giga in relation with bit and byte as powers of 1024 instead of 1000. Higher prefixes were not redefined by JEDEC.
In order to avoid this inconsistency, the International Electrotechnical Commission (IEC) has proposed the binary prefix which uses kibi [Ki], mebi [Mi], and gibi [Gi] for 1024¹, 1024², and 1024³ respectively.
The following table from Wikipedia gives an overview.