Torque to Horsepower & RPM Calculator (HP = T·RPM / 5252)
Calculate horsepower from torque and engine RPM, convert between lb-ft and Newton-meters (N·m), and analyze the dyno 5,252 RPM crossover point.
Calculated Results
Frequently Asked Questions
What is the mathematical relationship between torque and horsepower?
Horsepower is the rate at which work is performed over time, while torque is rotational twisting force. The fundamental formula is: Horsepower = (Torque in lb-ft × RPM) / 5,252.
Why do torque and horsepower curves always cross at 5,252 RPM on a dyno?
Because 1 horsepower is defined as 33,000 foot-pounds per minute (James Watt's definition). Since 1 revolution equals 2π radians, dividing 33,000 by 2π yields exactly 5,252.11. At 5,252 RPM, Torque (lb-ft) and HP are identical.
How does torque in lb-ft convert to Newton-meters (N·m)?
1 pound-foot (lb-ft) equals approximately 1.355818 Newton-meters (N·m). Conversely, 1 N·m equals 0.737562 lb-ft.
Which matters more for acceleration: torque or horsepower?
Both. Torque provides low-end acceleration off the line and hauling force, while horsepower determines peak speed and how rapidly the vehicle can accelerate through higher engine RPM bands.