EcoTrack

Wind Turbine Power Calculator

How much power does the wind actually deliver?

Air density (kg/m³)

Swept area (m²)

Wind speed (m/s)

Turbine efficiency (Cp)

Power output

548,800 W

What you entered

Air density (kg/m³): 1.225Swept area (m²): 5000Wind speed (m/s): 8Turbine efficiency (Cp): 0.35

1
v³ (wind speed cubed)
8³= 512
2
P = ½ρAv³Cp
0.5 × 1.225 × 5000 × 512 × 0.35= 548800 W

Result

Power output: 548,800 W

At this wind speed, the turbine generates about 548.8 kW.

Wind turbine power output by rotor size at 8 m/s and 12 m/s

Each row runs P = 0.5 x rho x A x v cubed x Cp with air density held at 1.225 kg/m3 (sea level, 15 C) and efficiency held at Cp = 0.35. Swept area is pi x (diameter / 2) squared, so the area column is the figure to type into the calculator for that rotor diameter.

Turbine	Rotor diameter (m)	Swept area (m2)	Power at 8 m/s (kW)	Power at 12 m/s (kW)
Rooftop micro turbine	2	3.1	0.3	1.2
Small farm turbine	5	19.6	2.2	7.3
Off-grid home turbine	7	38.5	4.2	14.3
Small commercial turbine	15	176.7	19.4	65.5
Community turbine	30	706.9	77.6	261.8
Mid-size onshore	50	1,963.5	215.5	727.4
Modern onshore	90	6,361.7	698.3	2,356.6
Large onshore	110	9,503.3	1,043.1	3,520.4
Offshore	130	13,273.2	1,456.9	4,916.9
Large offshore	160	20,106.2	2,206.9	7,448.1

Two patterns drive the whole table. Power scales with the square of rotor diameter, so doubling the blade length quadruples the output, and it scales with the cube of wind speed, so going from 8 to 12 m/s multiplies every row by 3.375. These are instantaneous outputs at one steady wind speed, not annual energy: a real turbine only sees its rated wind a fraction of the time, so onshore machines typically deliver 25 to 35 percent of nameplate over a year and offshore machines 40 to 50 percent. Real turbines also cut in around 3 to 4 m/s, cap output at their rated power well before 12 m/s on the larger rows here, and shut down near 25 m/s. Air density falls with altitude and rises in cold weather, and Cp can never exceed the Betz limit of 0.593.

Wind speed matters far more than anything else

Power scales with the cube of wind speed — doubling wind speed increases available power eightfold, which is why turbine siting (finding consistently windy locations) matters more than almost any other design choice.

Betz's limit caps real-world efficiency

No turbine can capture more than about 59.3% of the wind's kinetic energy (the Betz limit) — real turbines typically achieve 35-45% efficiency (Cp), which this calculator lets you set directly.

Frequently asked questions

A turbine with a 40 m rotor diameter in 12 m/s wind at sea level with 40% efficiency — how much power?

Swept area = π × 20² = 1,257 m². P = 0.5 × 1.225 × 1257 × 12³ × 0.40 = 0.5 × 1.225 × 1257 × 1728 × 0.40 ≈ 531 kW.

Why does doubling wind speed give 8 times the power?

Power depends on v³ (velocity cubed). Double the wind speed: 2³ = 8. This cubic relationship is why turbine sites are chosen for average wind speed above all other factors.

How is the wind turbine calculator different from the solar payback calculator?

This calculator estimates raw power output in watts from physical parameters. The solar payback calculator estimates financial break-even time. To compare wind vs solar financially, calculate annual energy from each and multiply by your electricity rate.