Watt-hours to Megawatt-hours (Wh to MWh)

1 watt-hour equals 0.000001 megawatt-hours exactly.

1 watt-hour = 0.000001 megawatt-hours

How to convert watt-hours to megawatt-hours

To convert watt-hours to megawatt-hours, multiply the number of watt-hours by 0.000001. This factor is exact. To go the other way, multiply megawatt-hours by 1,000,000.

megawatt-hours = watt-hours × 0.000001

Example: 10 watt-hours = 0.00001 megawatt-hours.

The 'calorie' on food labels is really a kilocalorie. The thermochemical calorie (4.184 J) is used here unless marked IT.

About these units

Watt-hour (Wh)

Metric (SI)Current unit

Exactly 3,600 joules, the energy used by a one-watt device in an hour. Battery capacities are quoted in watt-hours.

Pair a power unit with a unit of time and you get the watt-hour: one watt sustained for one hour, which works out to 3,600 joules. The watt itself was adopted at the second International Electrical Congress in 1889, in the same session that adopted the joule, so the two units share a birthday even though the watt-hour is the one people read off batteries.

Battery capacity is where it earns its keep. Multiplying amp-hours by the battery voltage gives an estimate of watt-hours, so a 2,500 mAh lithium-ion cell at 3.7 V holds roughly 9.25 Wh. That is why a 500 mA USB device runs about 3.7 hours on it rather than five: the cell voltage, not the 5 V from the port, sets the energy.

For scale, an alkaline AA battery holds about 9 kJ, which is 2.5 Wh. A 12 W LED lamp left on for an hour uses 12 Wh, and a 40 W appliance running for 25 hours uses 1,000 Wh.

1 watt-hour = 3,600 joules (exactly).

Sources: Wikipedia: Watt-hour; Wikipedia: Joule; Wikipedia: Orders of magnitude (energy)

Megawatt-hour (MWh)

Metric (SI)Current unit

1,000 kilowatt-hours. Used for power-plant output and wholesale electricity trading.

A megawatt-hour is a thousand kilowatt-hours, and it is where electricity stops being a household quantity and becomes an industrial one. It is the energy of a 1 MW load running for an hour, equal to 3.6 GJ, and it is used for metering large industrial customers and for the output of power plants.

The average US household used 893 kWh a month in 2020, so one megawatt-hour is a little more than a month of an ordinary home's electricity. Scaled up further, sustaining about 114 MW for a full year amounts to one terawatt-hour, the unit used for national generation figures.

Indian usage gives a neat link: a million of what Indians call units, meaning kilowatt-hours, is a gigawatt-hour, which is 1,000 MWh. Wholesale deals, plant ratings and grid statistics are typically quoted at this scale because the numbers stay readable.

1 megawatt-hour = 3,600,000,000 joules (exactly).

Sources: Wikipedia: Kilowatt-hour; Wikipedia: Watt-hour; Wikipedia: Orders of magnitude (energy)

Related conversions

See all energy units.