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)
- 230
- Amps (A)
- 0
- Resistance (Ω)
- 0
- Power (W)
- 1500
the result is:
- Current
- 6.52 A
- Voltage
- 230 V
- Current
- 6.522 A
- Resistance
- 35.267 Ω
- Power
- 1,500 W (1.5 kW)
Tips from the trade
- South African socket-outlets are rated at least 16 A (SANS 10142-1), so one outlet on 230 V can supply up to about 3.7 kW (230 × 16 = 3,680 W).
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and SANS 10400 (the National Building Regulations) and your local municipality before ordering.