Crankshaft Mathematics
- Enter the engine Horsepower (hp).
- Input the specific Engine Speed (RPM) where the power is measured.
- View the calculated Torque in lb-ft and Nm.
- Check the 5252 Law section to understand how your engine profile changes above and below that RPM crossover point.
Frequently Asked Questions
How is Torque calculated from Horsepower?
Torque (lb-ft) = (Horsepower × 5,252) / RPM. This is the standard physical formula used to measure twisting force at the crankshaft.
Why do Horsepower and Torque cross at 5252 RPM?
This is a mathematical constant in the Imperial system. Based on the definition of a 'horsepower' (moving 33,000 lbs one foot in one minute) and the geometry of a circle, the numbers must meet at 5,252.
What is the difference between lb-ft and Nm?
Pound-feet (lb-ft) is the Imperial unit for torque, while Newton-meters (Nm) is the Metric (SI) unit. 1 lb-ft is approximately equal to 1.356 Nm.
Which is more important: HP or Torque?
Torque is the internal twisting force that gets the vehicle moving (acceleration). Horsepower is the rate at which that work is performed (top speed and continuous power).
Performance Benefits
- Instant conversion from HP to Torque
- Provides both Imperial (lb-ft) and Metric (Nm) results
- Automated 5252 RPM crossover analysis
- Supports any engine speed or power level
- 100% private — your performance data stays local
- Mobile-optimized for checking specs on the go