What is megawatt?

A megawatt is a unit of power equal to one million watts. It is used to rate the output of power plants, large industrial facilities, and grid-scale renewable energy installations.

Real-world uses

Megawatts describe the output of power plants, wind turbines (typically 2–15 MW each), and large solar farms. A modern natural gas peaker plant might produce 50–500 MW. Data centres may have power demands of tens to hundreds of MW. Grid operators manage supply and demand in MW.

History

As electrical grids grew through the 20th century, the megawatt became the standard unit for power station output and grid management. It enables comparisons across coal, gas, nuclear, and renewable generation sources on a common scale.

Common mistakes

Confusing MW (power) with MWh (energy). A 100 MW power plant running for 10 hours generates 1,000 MWh (1 GWh) of energy. Also, not distinguishing between MW of capacity (nameplate) and MW of actual output (which varies for renewables).

What is gigawatt?

A gigawatt is a unit of power equal to one billion watts. It is used to express the total power output of national electricity grids, large power stations, and national energy policy targets.

Real-world uses

Gigawatts describe the generating capacity of entire national grids, large hydroelectric dams (Three Gorges Dam: ~22.5 GW), and the total installed solar or wind capacity of countries. Global electricity demand is often expressed in terawatts (1,000 GW). Energy policy discussions use GW to compare national ambitions.

History

Gigawatts entered common use in discussions of national and continental electricity systems during the 20th century. As installed generation capacity in large countries reached the gigawatt scale, this unit became standard for energy policy, grid planning, and international energy statistics.

Common mistakes

Confusing GW (power) with GWh (energy). A 22 GW dam running at full capacity for one hour generates 22 GWh of energy. Also, the pop-culture reference "1.21 gigawatts" from Back to the Future is frequently cited but would equal about 1,210 MW—a large power plant.

When is this conversion used?

Converting megawatt to gigawatt is useful in the power domain when comparing values across different measurement standards or applying formulas that require a specific unit.

Worked examples

1 megawatt = 0.001 gigawatt

1 gigawatt = 1.000000e+09 watt

How to convert megawatt to gigawatt

To convert megawatt to gigawatt, multiply the value by 0.001.

To convert gigawatt back to megawatt, multiply by 1,000.

Measurement standards

The watt is the SI derived unit of power, defined as one joule per second (kg·m²/s³). Horsepower remains in widespread informal use, particularly in the automotive industry, but has no single universal definition across regions.

Did you know?

The human body at rest produces about 80 watts of power — roughly enough to keep an incandescent light bulb glowing. During intense exercise, a trained cyclist can sustain over 400 watts, and elite sprinters briefly exceed 2,000 watts.

Quick reference: megawatt to gigawatt

megawattgigawatt
0.10.0001
0.50.0005
10.001
20.002
50.005
100.01
250.025
500.05
1000.1
2500.25
5000.5
1,0001

Common values

megawattgigawatt
LED light bulb0.00001 megawatt1.000000e-08 gigawatt
Desktop computer0.0003 megawatt3.000000e-07 gigawatt
Microwave oven0.001 megawatt0.000001 gigawatt
Small car engine0.075 megawatt0.000075 gigawatt
Wind turbine (large)3 megawatt0.003 gigawatt