Motor torque calculator
Work out the rated torque a three-phase motor delivers from its power and shaft speed — the first figure used to size a gearbox, coupling or conveyor drive. Enter power in kilowatts or horsepower, then read torque in N·m — or work backwards from a required torque to the minimum motor power.
Motor torque from power & speed
Formula: T (N·m) = 9550 × P (kW) / n (RPM)
Reverse mode — power from torque & speed
Formula: P (kW) = T (N·m) × n (RPM) / 9550, using the same shaft speed entered above.
Rated torque at the motor shaft is the first figure used to size a gearbox, coupling or conveyor drive. AO Ctrl stocks the motors, gearboxes and drive control for industrial motion:
Frequently asked questions
How do I calculate the rated torque of a motor?
Rated torque is T (N·m) = 9550 × P (kW) / n (RPM). With the default 4 kW motor at 1450 RPM, torque is 9550 × 4 / 1450 ≈ 26.3 N·m. Enter power in kW or hp (hp is converted with hp × 0.7457 kW) and shaft speed in RPM to get the figure used to size a gearbox, coupling or conveyor drive.
How do I find the motor power needed for a required torque?
Work backwards with P (kW) = T (N·m) × n (RPM) / 9550. The calculator reverse mode does this in one step — for example, 26.4 N·m at 1450 RPM needs 26.4 × 1450 / 9550 ≈ 4.0 kW, shown in both kW and hp. Use this to pick the minimum motor size for a known load torque.
What is the difference between rated torque and starting torque?
Rated (running) torque is the continuous torque the motor delivers at its rated power and speed, calculated here as 9550 × P / n. Starting or locked-rotor torque is the torque available during acceleration and can be several times higher. The calculator sizes the continuous rated value; for high-inertia loads you still need to check starting torque against the load.