Kilowatt-Hour (kWh)
The standard unit of electrical energy billing: one kilowatt of power drawn for one hour.
A kilowatt-hour is the amount of energy used by a 1,000-watt device running for one hour, and it is the unit your electricity company charges for. To find a mining rig's consumption, multiply its measured wattage by hours run and divide by 1,000: a 400W rig over 24 hours uses 9.6 kWh. Multiplying total kWh by your effective per-kWh rate gives the actual cost in money. Every home-mining cost estimate ultimately reduces to kWh, which is why measuring real wattage rather than trusting the power supply label matters so much. Monthly bills report total kWh used, letting you back out your true blended rate.