Horsepower Calculator
Calculate horsepower from torque and RPM.
Engine Specifications
lb-ft
Revolutions per minute
Horsepower
Horsepower (HP)
190.40 HP
Kilowatts (kW)
141.98 kW
Metric Horsepower (PS)
193.04 PS
Torque:
200.00 lb-ft (271.16 Nm)
@ 5000 RPM
Formula:
HP = (Torque × RPM) ÷ 5252
= (200.00 × 5000) ÷ 5252
= 190.40 HP
About This Calculator
The Horsepower Calculator calculates horsepower from torque and RPM (revolutions per minute). Horsepower is a unit of power that measures the rate at which work is done. This calculator uses the standard formula: HP = (Torque × RPM) / 5252.
Enter the torque value (in lb-ft or Nm) and the RPM, and the calculator will compute the horsepower. The calculator also provides the equivalent power in kilowatts and metric horsepower (PS) for reference.
Formula & Calculation Method
Horsepower Calculation:
Horsepower Formula:
HP = (Torque × RPM) ÷ 5252
Where:
Torque = Rotational force (lb-ft or Nm)
RPM = Revolutions per minute
5252 = Conversion constant
Conversions:
1 HP = 0.7457 kW
1 HP = 1.01387 PS (metric horsepower)
1 lb-ft = 1.35582 Nm
The constant 5252 comes from the conversion between rotational work and linear work. At 5252 RPM, horsepower equals torque (in lb-ft). This is why torque and horsepower curves always cross at 5252 RPM on a graph.
How to Use This Calculator
- Select Torque Unit: Choose lb-ft (pound-feet) or Nm (Newton-meters).
- Enter Torque: Input the torque value from your engine specifications.
- Enter RPM: Input the engine speed in revolutions per minute.
- View Results: See horsepower, kilowatts, and metric horsepower calculated.
Frequently Asked Questions
What is horsepower?
Horsepower (HP) is a unit of power that measures the rate at which work is done. One horsepower is approximately equal to 745.7 watts. It was originally defined as the power needed to lift 550 pounds one foot in one second.
Why is 5252 used in the formula?
The constant 5252 comes from unit conversions between rotational work and linear work. It's derived from: 1 HP = 550 ft-lb/s, and when converting RPM to radians per second and accounting for the conversion factors, you get 5252. At 5252 RPM, horsepower equals torque (in lb-ft).
What is the difference between horsepower and torque?
Torque is rotational force - it's the twisting force that the engine produces. Horsepower is the rate at which work is done - it's calculated from torque and RPM. High torque at low RPM provides good acceleration, while high horsepower at high RPM provides high top speed.
What is a good horsepower for a car?
Horsepower needs vary by vehicle type and intended use. Economy cars typically have 100-150 HP, midsize sedans 150-250 HP, sports cars 250-400 HP, and high-performance vehicles 400+ HP. The power-to-weight ratio is often more important than raw horsepower.
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The NumCalculators Editorial Team consists of subject matter experts across various fields who review and verify the accuracy of our calculators. Each calculator undergoes rigorous testing and validation before publication.