Engine Horsepower Calculator
Use the standard automotive power equation to convert an engine's rotational torque into mechanical horsepower, PS, and kilowatts.
HP & Engine Power Calculator
Understanding Horsepower and Torque
In the automotive world, the relationship between Horsepower (HP) and Torque is often misunderstood. While both measure the output of an engine, they represent different physical properties of the powertrain.
What is Torque?
Torque is the measure of twisting force. When combustion pushes down a piston, it turns the crankshaft. The twisting force applied to that crankshaft is torque. In simple terms: torque is what gets a vehicle moving. It is typically measured in pound-feet (lb-ft) in the US, or Newton-meters (Nm) in metric regions.
What is Horsepower?
Horsepower is a measure of power, which is defined as the rate at which work is done over time. While torque tells you how much force is applied, horsepower tells you how quickly that force is being applied. Horsepower is what keeps a vehicle moving fast.
The Mathematical Relationship
Because horsepower is fundamentally linked how fast the engine is spinning, you can always calculate the exact horsepower output of an engine if you know its torque output at a specific RPM. The formula for mechanical horsepower is:
Due to this mathematical constant, on a standard engine dyno graph displaying torque in lb-ft, the torque curve and the horsepower curve will always perfectly intersect at precisely 5,252 RPM.
Metric Conversions
- PS (Pferdestärke): Often used in Europe to denote "Metric Horsepower." 1 Mechanical HP equals roughly 1.014 PS.
- kW (Kilowatts): The modern standard measure for power used globally and on electric vehicles. 1 Mechanical HP equals exactly 0.7457 kW.