Wind Turbine Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Wind power is extremely sensitive to wind speed, so a small change in the assumed breeze can create a large change in predicted output. This calculator combines rotor geometry, air density, turbine efficiency, wake and system losses, and tip-speed ratio to show both available wind power and a simplified usable-output scenario.

What this calculator does

The Wind Turbine Calculator handles horizontal-axis and vertical-axis geometries. It estimates swept area, available wind power, output after turbine and system losses, real efficiency, rotor RPM, torque, annual energy, and tariff-based revenue. Horizontal-axis area uses blade length as radius; vertical-axis area uses rotor diameter × rotor height.

How to use it

Choose HAWT or VAWT and enter the geometry fields shown for that type. Add wind speed, air density, turbine efficiency, wake loss, mechanical, electrical, transmission and downtime losses, electricity tariff, and tip-speed ratio. Use a wind speed representative of the rotor height; a nearby ground-level weather reading may not represent turbine conditions.

How the calculation works

Available wind power is ½ρAv³. The calculator applies turbine efficiency and wake loss, then multiplies the remaining power by the complements of mechanical, electrical, transmission, and downtime losses. Rotor RPM is estimated from wind speed, tip-speed ratio, and rotor circumference; torque is output power divided by angular velocity. Annual energy assumes the calculated output persists for 8,760 hours.

Example

For the default HAWT with 5 m blades, 8 m/s wind, 1.225 kg/m³ air, 35% turbine efficiency and the listed losses, swept area is about 78.54 m². Available wind power is about 24.63 kW, while modeled output after losses is about 7.03 kW, with roughly 91.7 rpm at TSR 6.

How to interpret the result

The gap between available wind power and output shows how much the efficiency and loss assumptions matter. Wind speed matters even more because power scales with v³. Treat annual energy and revenue as a sensitivity scenario: they assume the entered wind-speed condition represents the entire year, which is rarely true at a real site.

Limitations and notes

A proper wind-energy assessment uses a wind-speed distribution, turbine power curve, cut-in, rated and cut-out behavior, hub-height shear, turbulence, array wake modeling, availability, and grid constraints. This calculator applies a single wind speed and simplified multiplicative losses. It is useful for physics and early scenario comparison, not bankable energy-yield prediction.