Engine Horsepower Calculator — Free Online Calculator & Formula Guide
Calculate engine horsepower from torque and RPM using the classic formula HP = (Torque x RPM) / 5252. Free, instant, and accurate.
Engine Horsepower Calculator
Results below
Enter Values
Power (kW)
273.32 kW
Torque
350.0 lb-ft
at RPM
5500 RPM
Formula
(350.0 × 5500) / 5252 = 366.5 HP
Power Category
▲ Performance
About 5252
The constant 5252 comes from the definition of horsepower: 1 HP = 550 ft·lb/s. When converting RPM to radians per second and torque to work, the math simplifies to HP = (Torque × RPM) / 5252. At exactly 5252 RPM, torque and horsepower are always equal — this is why the torque and HP curves cross at 5252 RPM on every dyno graph.
Scenario Comparison
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Horsepower Output
366.5 HP
Horsepower
366.5 HP
Kilowatts
273.32 kW
Torque
350.0 lb-ft
Engine Speed
5500 RPM
Step-by-Step Formula
(350.0 × 5500) / 5252 = 366.5 HP
Torque & HP Curves
Torque (blue) and HP (red) curves cross at exactly 5,252 RPM
The constant 5252 comes from the definition of horsepower: 1 HP = 550 ft·lb/s. When converting RPM to radians per second and torque to work, the math simplifies to HP = (Torque × RPM) / 5252. At exactly 5252 RPM, torque and horsepower are always equal — this is why the torque and HP curves cross at 5252 RPM on every dyno graph.
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