Energy land, checked. Solar, wind, battery, and data-center projects, the permits they need, and the grid they plug into. Start here →
Parcel & Grid

Home › Guides › Energy questions

What is the difference between a megawatt and a megawatt-hour?

Updated

General information, not a substitute for the advice of an attorney.

Short answer: A megawatt (MW) is a rate, like miles per hour; a megawatt-hour (MWh) is a quantity, like miles traveled. EIA's own example: a plant with 100 MW of capacity running continuously for 24 hours produces 2,400 MWh, and running the whole year it would produce 876,000 MWh (EIA FAQ). Almost no plant runs at full capacity all year, which is why "capacity" and "generation" are different numbers.

Capacity vs. generation

EIA says the amount of electricity a plant generates depends on its generation capacity and on how long its generators actually run at that capacity (EIA). Capacity is the nameplate, in MW. Generation is what came out over a period, in MWh. The ratio between the two over a year is the capacity factor, which EIA defines as a measure of generation capacity relative to generation (EIA). A plant that produced 438,000 MWh against a 876,000 MWh maximum would have a 50% capacity factor (our arithmetic from EIA's example).

  • 1 MW = 1,000 kilowatts (kW). 1 MWh = 1,000 kilowatt-hours (kWh), the unit on a home bill.
  • MW x hours = MWh. 100 MW x 24 h = 2,400 MWh (EIA).
  • A battery is rated both ways: MW is how fast it can discharge, MWh is how much it holds. ERCOT reports its storage queue as 171 GW and 410 GWh, which works out to about 2.4 hours of discharge at full power (our arithmetic from ERCOT, July 29, 2026).

Why "homes per megawatt" is not a fixed number

Press releases often translate MW into homes served. The conversion requires two assumptions, and both vary. First, how much a home uses: EIA reports the average US residential customer bought 10,791 kWh in 2022 (about 899 kWh a month), but Louisiana averaged 14,774 kWh and Hawaii 6,178 kWh (EIA FAQ, updated January 8, 2024). Second, how much the plant actually produces, which depends on its capacity factor: a 100 MW plant at 100% output could cover 876,000 MWh divided by 10.791 MWh, or roughly 81,000 average homes a year; the same plant at a 25% capacity factor covers about a quarter of that (our arithmetic from the two EIA pages above). A MW of solar, wind, gas, and nuclear therefore serve very different numbers of homes, and none of them serve those homes at every hour. Treat any "homes powered" claim as a rough annual-energy comparison, not a statement about who stays lit on a still winter night.

See how many acres a solar farm needs, how much land battery storage needs, and the ERCOT queue.

General information from the sources linked above, not legal, tax, or financial advice.

Sources and helpful links

More official contacts and resources: Helpful links.

Browse resources