About this calculator
Enter any two of voltage, current, resistance and power to get the other two. Handy for checking appliance loads on a circuit.
How it’s calculated
V = I × R, and P = V × I. For AC loads with a power factor below 1, real current will be higher.
Worked example
With these inputs:
- Volts (V)
- 120
- Amps (A)
- 0
- Resistance (Ω)
- 0
- Power (W)
- 1500
the result is:
- Current
- 12.5 A
- Voltage
- 120 V
- Current
- 12.5 A
- Resistance
- 9.6 Ω
- Power
- 1,500 W (1.5 kW)
Tips from the trade
- A 15 A, 120 V circuit carries 1,800 W, and you should plan for 80% (1,440 W) continuous.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and local building codes before ordering.