Single Phase Power Calculator
Calculate single-phase power, current and cable loading from load and power factor.
About Single Phase Power Calculator
Current is the load divided by voltage, power factor and efficiency, since each reduces the useful output for a given current. Protective devices are sized above full-load current to avoid nuisance tripping. A 3.5 kW load at 230 V draws about 16 A, which is why domestic ring circuits and appliance ratings cluster around that figure.
Formula
Single Phase Power
I = P ÷ (V × power factor × efficiency)
- breaker sizing
- Typically 125% of full-load current for continuous loads
Worked example
With the default values below, Single Phase Power Calculator returns Line Current of 16.018. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Supply voltageminimum 1 V
- 230 V
- Loadminimum 0 kW
- 3.5 kW
- Power factoraccepts 0.01–1
- 0.95
- Load efficiencyaccepts 0–100 %
- 100 %
Results
- Line Current
- 16.018 A
- Apparent Power
- 3.6842 kVA
- Input Power Drawn
- 3.5000 kW
- Recommended Breaker Size
- 21 A
- Annual Energy at 8 Hours a Day
- 10,220.0 kWh
Step by step
- 1Values used
- 2Single Phase Power
- 3Line Current= 16.018 A
- 4Apparent Power= 3.6842 kVA
- 5Input Power Drawn= 3.5000 kW
- 6Recommended Breaker Size= 21 A
- 7Annual Energy at 8 Hours a Day= 10,220.0 kWh
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Single Phase Power calculated?
I = P ÷ (V × power factor × efficiency) Current is the load divided by voltage, power factor and efficiency, since each reduces the useful output for a given current. Protective devices are sized above full-load current to avoid nuisance tripping.
Why does Single Phase Power matter?
A 3.5 kW load at 230 V draws about 16 A, which is why domestic ring circuits and appliance ratings cluster around that figure.
What values do I need to enter?
This calculator takes 4 inputs: Supply voltage, Load, Power factor, Load efficiency. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.