Definition
Hashrate units express how many SHA-256 computations a miner or the whole network performs each second. The base unit is the hash per second (H/s), but practical mining uses much larger multiples. Knowing the scale lets you compare a single machine to a farm or to the entire Bitcoin network at a glance.
The common units
The units climb by factors of one thousand. A terahash per second (TH/s) is one trillion (10^12) hashes per second, the typical scale for an individual modern ASIC. A petahash per second (PH/s) is one quadrillion (10^15) hashes, the scale of a sizeable mining facility. An exahash per second (EH/s) is one quintillion (10^18) hashes, the scale used to describe large pools and the total network. Smaller units like gigahash (GH/s) and megahash (MH/s) describe hobby-class and open-source devices.
Why the unit matters
Hashrate is the single best proxy for how much work a miner contributes and, in turn, its share of expected rewards. The network's combined hashrate, measured in hundreds of EH/s, also feeds directly into difficulty adjustments that keep block intervals near ten minutes. When comparing machines, always check the unit and prefix, mixing up TH and PH overstates a miner by a factor of a thousand.
The figure these units quantify is a device's hashrate, the value pools convert into accepted shares.
In Simple Terms
Hashrate units express how many SHA-256 computations a miner or the whole network performs each second. The base unit is the hash per second (H/s),…