⚙️ Torque to Horsepower Calculator
Compute mechanical power using torque and rotational speed.
Enter the torque and RPM of a rotating shaft to determine horsepower, kilowatts, and watts. Ideal for sizing motors, comparing engines, or estimating drive performance.
Enter positive or negative torque. Decimals are supported.
RPM must be non-negative. Use zero for static torque.
Torque (lb·ft)
250
Torque (N·m)
338.9545
Horsepower (HP)
85.682
Kilowatts (kW)
63.893
Watts: 63,893
How to Use This Calculator
Enter torque
Provide torque in lb·ft or N·m. Switch units using the dropdown.
Specify RPM
Input rotational speed to compute mechanical power. Zero RPM yields zero horsepower.
Review horsepower and kW
Results include HP, kW, W, and torque conversions for documentation or comparisons.
Formula
HP = (Torque(lb·ft) × RPM) ÷ 5252
kW = HP × 0.745699872
The constant 5252 derives from 33,000 ft·lbf/min (1 horsepower) divided by 2π ≈ 6.28318.
Use the formula breakdown to confirm the calculation logic or perform the conversion manually if needed.
Full Description
Horsepower quantifies mechanical power—the rate at which torque does work while an object rotates. This calculator uses the classic relationship between torque, RPM, and horsepower, accommodating both imperial and SI torque units.
Kilowatt outputs help compare electric motor ratings, while maintaining traditional HP values for internal combustion engines and legacy specifications.
Pair this tool with the Newton Meter Calculator to derive torque first, or with the Nm to Ft-Lbs Converter when you need to deliver results in imperial units for torque wrenches and datasheets.
Frequently Asked Questions
What happens at zero RPM?
Horsepower equals zero because no work is performed over time, even if torque is present (static load).
Why 5252?
It comes from converting between rotational speed, torque, and power with consistent units (lb·ft, RPM, horsepower).
Can I use SI torque directly?
Yes. Select Newton-meters from the unit dropdown—the calculator converts to lb·ft internally before calculating horsepower.
What about efficiency or losses?
This equation gives ideal mechanical power. Real-world systems experience losses; apply efficiency factors separately if needed.