Enter the voltage (V or kV), the current (amps), and the rotational speed (RPM) into the calculator to determine the torque.
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Torque from kV Formula
The following formula is used to estimate torque from voltage, current, and rotational speed.
T = \frac{60 \times V \times I}{2\pi \times RPM}- Where T is the torque (N⋅m)
- V is the voltage (V). If you use kilovolts, 1 kV = 1000 V.
- I is the current (A)
- RPM is the rotational speed (revolutions per minute)
Note: This is an ideal, power-based estimate using electrical power (V×I) and mechanical power (T×ω). Real systems may differ due to efficiency, power factor (AC), losses, and motor/controller characteristics. This page uses kV to mean kilovolts (voltage), not a motor’s Kv speed constant (RPM/V).
| Kilovolts (kV) | Torque (N⋅m) |
|---|---|
| 0.05 | 1.592 |
| 0.1 | 3.183 |
| 0.2 | 6.366 |
| 0.24 | 7.639 |
| 0.36 | 11.459 |
| 0.48 | 15.279 |
| 0.6 | 19.099 |
| 0.75 | 23.873 |
| 1 | 31.831 |
| 1.2 | 38.197 |
| 1.5 | 47.746 |
| 1.8 | 57.296 |
| 2 | 63.662 |
| 2.4 | 76.394 |
| 2.5 | 79.577 |
| 3 | 95.493 |
| 3.3 | 105.042 |
| 3.6 | 114.592 |
| 4 | 127.324 |
| 5 | 159.155 |
| *Assumes Current = 10 A and Rotational Speed = 3000 RPM. Formula used: Torque = (60 × (kV × 1000) × Current) / (2 × π × RPM). Under these assumptions, 1 kV ≈ 31.831 N⋅m. | |
How to Calculate Torque from kV?
The following example problems outline how to calculate torque from voltage, current, and rotational speed.
Example Problem #1
- First, determine the total kilovolts (kV). In this example, the total kilovolts (kV) is given as 5 kV.
- Next, determine the current (amps). For this problem, the current (amps) is given as 13 A.
- Next, determine the rotational speed (RPM). In this case, the rotational speed (RPM) is found to be 5 RPM.
- Finally, calculate the torque using the formula above.
Tkv = (60*kV*1000*I)/(2*pi*RPM)
Inserting the values from above and solving yields:
Tkv = (60*5*1000*13)/(2*3.1415*5) = 124144.52 (N⋅m)
Example Problem #2
Using the same method as above, determine the variables required by the equation. For this example problem, these are provided as:
total kilovolts (kV) = 7
current (amps) = 9
rotational speed (RPM) = 7
Entering these given values yields:
Tkv = (60*7*1000*9)/(2*3.14159*7) = 85943.70 (N⋅m)
