Calculators
Torque from power and speed
Torque follows from power and speed, the shortest useful formula in drive engineering. You need it for every gearbox selection and every check whether a motor will start the machine at all.
Result
- Torque
- —Nm
- Angular velocity
- —rad/s
Please fill all fields with valid numbers.
A guide, not a design to standard. We give no warranty for the correctness of the results. The applicable standards and case-by-case verification govern.
The grey values are an example. Simply enter your own.
Matching services
Calculating is the easy part.
A formula gives you a number. Designing a plant also demands installation method, grouping, discrimination, the standards in force and a look at the installed base. That is what we take on.
Worked example
The default case the calculator starts with, worked through once. Change the values above and it recalculates immediately.
Inputs
- Shaft power
- 7.5 kW
- Speed
- 1,450 min⁻¹
Result
- Torque
- 49.4 Nm
- Angular velocity
- 152 rad/s
Formula and standards
Formula
- M = 9550 · P / n (P in kW, n in min⁻¹, M in Nm)
- ω = 2π · n / 60
Assumptions and standards
- The constant 9550 comes from 60,000 / 2π and applies to power in kilowatts and speed in revolutions per minute.
- The result is rated torque at the operating point. Starting, pull-up and breakdown torque differ considerably and are given in the motor data sheet.
Does the formula apply to geared motors?
Yes, if you enter the output speed. Output torque rises with the gear ratio, less the gearbox efficiency.
Why is rated torque not enough for sizing?
Because the critical point is usually starting. A machine with high breakaway torque needs a multiple of rated torque, starting torque governs there, not the value calculated here.
Contact
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