Horsepower Calculator
Calculate mechanical horsepower from engine torque (lb-ft) and RPM using the standard HP = torque x RPM / 5252 formula.
Calculator Inputs
Engine torque in pound-feet. Must be zero or a positive number.
Engine speed in revolutions per minute. Must be zero or a positive number.
- Horsepower
- 228.48
About these results
CalcSpectrum calculators produce automated estimates using established formulas and the specific values you enter. Because real-world outcomes depend on input accuracy, mathematical assumptions, and rounding conventions, please verify critical figures with an appropriately qualified financial, tax, medical, legal, or other professional, as relevant.
How It's Calculated
Formula
This calculator computes mechanical horsepower from engine torque and rotational speed (RPM), using the standard formula HP = (torque in lb-ft x RPM) / 5252. The constant 5252 comes from the definition of one horsepower (33,000 ft-lbf per minute) combined with the conversion from RPM to angular velocity; 5252 is the conventional, industry-standard rounded value used across automotive and engineering references. This calculator computes torque-and-RPM horsepower directly and is not the same as the separate Engine Horsepower calculator, which estimates horsepower from vehicle weight and quarter-mile trap speed/time.
Worked Examples
525.2 lb-ft at 1000 RPM
- HP = (525.2 x 1000) / 5252 = 100 HP.
Frequently Asked Questions
Why is the constant 5252 and not a rounder number?
It derives from the physical definition 1 horsepower = 33,000 ft-lbf/min combined with the RPM-to-radians-per-second conversion (2*pi/60). The exact value is approximately 5252.113, and 5252 is the conventional rounded constant used throughout the automotive and engineering industry.
At what RPM do torque and horsepower always cross on a dyno chart?
At 5252 RPM, torque (lb-ft) and horsepower are numerically equal — this is a direct consequence of the formula's denominator, not a coincidence.
Is this the same as the Engine Horsepower calculator?
No. This calculator computes horsepower directly from torque and RPM. The Engine Horsepower calculator instead estimates horsepower from vehicle weight and quarter-mile elapsed time/trap speed — a different method for a different situation.