T = torque (N·m)
Power, speed and torque
Converts transmitted mechanical power and rotational speed to torque.
FORMULA REFERENCE
T = 60P/(2πN) = 9550P(kW)/N(rpm)
Converts transmitted mechanical power and rotational speed to torque.
Variables and units
Keep each value in the units shown below before substituting it into the displayed relation. Convert first rather than mixing unit systems inside one calculation.
P = mechanical power (W or kW)
N = speed (rpm)
WORKED EXAMPLE
Calculate the stated condition, then interpret its boundary.
Known values
- P = 15 kW
- N = 1,440 rpm
Substitution: T = 9,550 × 15 / 1,440
Calculated result: T = 99.5 N·m
Engineering interpretation: At the same power, reducing speed increases torque and often increases the required shaft capacity.
Conditions, limitations and review
- Steady mechanical power transmission
- Power is transmitted at the stated shaft speed
Use this formula to understand or screen the stated engineering condition. A final design requires the governing standard, actual loads, material condition, manufacturing features and professional engineering judgement.
Source: NIST Special Publication 811 for SI units; relation derived from P = Tω and ω = 2πN/60.