Single Phase Current Calculator

Q: What is the formula for single phase current?

I = (kW × 1000) ÷ (V × PF). For example, 5 kW at 230V with PF=0.9: I = 5000 ÷ (230 × 0.9) = 24.15A.

Q: What voltage is used for single phase?

In the US: 120V or 240V. In the UK/EU: 230V. In Australia: 230V. Single phase is the standard for homes and small commercial premises.

Q: When do I use single phase vs three phase?

Single phase is standard for homes, small offices, and loads up to about 10 kW. Three phase is used for larger loads, industrial equipment, and commercial buildings where balanced three phase power is available.

Calculate the current in amps for a single phase AC circuit. Enter power in kW, voltage, and power factor to get amps and VA rating instantly.

This calculator provides estimates only. Always consult a qualified electrician for real installations.

Calculate Single Phase Current

Power (kW)

Voltage (V)

Power Factor

Result

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Current (Amps)

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Apparent Power (VA)

Formula

I (Amps) = (kW × 1000) ÷ (Volts × Power Factor)

This is the real current the circuit must carry. Wire and breaker sizing should be based on this ampere value.

Example Calculation

A 7.5 kW electric water heater connected to a 240V single phase supply at PF = 1.0:

I = (7.5 × 1000) ÷ (240 × 1.0) = 7500 ÷ 240 = 31.25 A
Apparent power = 7,500 VA = 7.5 kVA

This circuit would need a 40A breaker (31.25A × 1.25 = 39.06A continuous load requirement).

Frequently Asked Questions

What is the formula for single phase current?

I = (kW × 1000) ÷ (V × PF). Alternatively in watts: I = Watts ÷ (V × PF). Always use the rated power factor of the load for accuracy.

What voltage is used for single phase?

US: 120V for most outlets, 240V for large appliances. UK/EU/Australia: 230V for standard supplies. Always use the actual supply voltage for your region.

When do I use single phase vs three phase?

Single phase is standard for residential and light commercial up to ~10 kW. Three phase is more efficient for loads above 10 kW and industrial equipment. Use the 3-phase current calculator for three phase circuits.