Current from power Calculator: measuring notes and method
Distinguish input from output power
Enter the electrical input watts. A motor’s mechanical output rating is not its electrical input; substituting it without accounting for efficiency can understate current.
CHECK A PRACTICAL EXAMPLE
The same DC power at two voltages
For an ideal load taking 24 W of electrical input, compare the supply voltages.
12 V DC
- Current
- 2 A
24 V DC
- Current
- 1 A
The arithmetic current halves when voltage doubles at fixed input power. This does not establish that a device can be connected to either voltage; use its rated supply.
Fixed comparison in metric units. Values are illustrative unless linked to a recorded project; changing the calculator above does not change this example.
Formula
Current (A) = power (W) ÷ voltage (V).
Product reference: Fluke electrical glossary
Worked example
Illustrative values match Reset example and stay fixed when you edit the calculator.
Starting-value worked example
- Power
- 2,300 W
- Voltage
- 230 V
Current: 10 A
Follow the calculation
- Current = 2,300 W ÷ 230 V = 10 A under this model.
AC current and power factor
For single-phase AC, current is real input power divided by RMS voltage and true power factor. A 1,840 W load at 230 V and power factor 0.8 draws 10 A; this tool assumes power factor 1 and would show 8 A. Three-phase circuits require a different relationship.
Reviewed 19 October 2026. How calculations are checked · Report a correction