# Shaft Power Calculator Calculate the power transmitted by a rotating shaft. P = T·ω = 2π·n·T/60. Solve power from torque and speed, or torque from power and speed. Supports W/kW/hp. > Canonical page: https://elysiatools.com/en/tools/shaft-power-calculator - **Category:** Math & Numbers - **Keywords:** shaft power, rotational power, torque, angular velocity, rpm, horsepower, mechanical engineering ## Overview The Shaft Power Calculator helps mechanical engineers and technicians quickly determine the power transmitted by a rotating shaft or calculate the required torque. By applying the fundamental rotational physics formula P = T·ω = 2π·n·T/60, the tool solves for either power or torque based on your rotational speed (rpm) and selected units, supporting Watts, Kilowatts, and Horsepower. ## Inputs - **Calculation Mode** (select) - **Torque T (N·m)** (number): Shaft torque in N·m. Required in Power mode. - **Rotational Speed n (rpm)** (number): e.g. 1500 - **Power P** (number): Shaft power, in the selected power unit. Required in Torque mode. - **Power Unit** (select) - **Decimal Places** (number) ## When to use - When designing or selecting electric motors, gearboxes, or drive shafts and you need to verify power transmission limits. - When you have measured the rotational speed (rpm) and torque of a shaft and need to calculate the output power in kW or horsepower. - When you know the target power rating of a system and need to determine the minimum torque capacity required for the shaft at a specific operating speed. ## How it works - Select the calculation mode: either calculate power from torque and speed, or calculate torque from power and speed. - Enter the known parameters, including the rotational speed in rpm, and either the torque in N·m or the power in your preferred unit. - Choose your target power unit (W, kW, or hp) and specify the desired decimal precision. - Click calculate to instantly compute the missing value along with the corresponding angular velocity in radians per second. ## Use cases - Sizing electric motors by calculating the required torque at a specific operating RPM. - Analyzing industrial machinery performance by converting measured shaft torque and speed into output kilowatts. - Converting horsepower ratings of automotive engines to torque values at specific engine speeds. ## Frequently asked questions ### What formula does this calculator use? It uses the standard rotational power formula: P = T · ω, where ω (angular velocity) is calculated as 2π · n / 60 (with n in rpm). ### What units of power are supported? The calculator supports Watts (W), Kilowatts (kW), and Horsepower (hp). ### Can I calculate torque if I only know the horsepower and RPM? Yes, switch the calculation mode to 'Torque from power and speed', enter the power in hp and speed in rpm, and the tool will output the torque in N·m. ### What is the relationship between angular velocity and RPM in this tool? Angular velocity (ω) in radians per second is calculated directly from the rotational speed (n) in rpm using the formula ω = 2π · n / 60. ### Does this calculator account for transmission efficiency losses? 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