What power factor should I use in the amperage calculator?

If you do not know the exact power factor, typical values for many loads are around 0.8 to 0.95. Motors and transformers often have power factors in this range. When in doubt, 0.8 is a conservative starting point.

Is the watts to amps conversion the same for DC and AC?

No. For DC, current is simply watts divided by volts. For AC you must consider power factor, and for three-phase circuits the geometry of the three phases adds √3 or 3 into the formula.

Why does current increase when voltage drops for the same load?

To deliver the same power at a lower voltage, more current must flow. Because P = V × I × PF, if power and power factor stay about the same and voltage falls, the current must rise to balance the equation.

Amperage Calculator

Q: How do I convert watts to amps?

For direct current (DC), divide power in watts by voltage in volts: I = P ÷ V. For AC you also divide by the power factor and, in three-phase systems, by √3 or 3 depending on whether you use line-to-line or line-to-neutral voltage.

Q: How do I calculate amps in a single-phase AC circuit?

For single-phase AC, current in amps is calculated as I = P ÷ (V × PF), where P is power in watts, V is RMS voltage, and PF is the power factor between 0 and 1.

Q: How do I calculate amps in a three-phase circuit?

For three-phase line-to-line voltage use I = P ÷ (√3 × V × PF). For three-phase line-to-neutral voltage use I = P ÷ (3 × V × PF). P is power in watts, V is voltage, and PF is power factor.

Q: How many amps is 1 kW at 230 V?

In a 230 V single-phase circuit with power factor 1, 1 kW draws about 4.35 A (1000 ÷ 230). With a power factor of 0.8, the same 1 kW draws roughly 5.43 A.

Enter power, voltage and power factor to get current in amps for DC, single-phase and three-phase circuits. Results update as you type.

Decimals:

Current type

▾

Choose DC or AC. Three-phase supports both line-to-line and line-to-neutral voltage.

Voltage

Use RMS voltage (line-to-line or line-to-neutral as selected).

Power

Enter real power, not apparent power (kVA).

Power factor

Used for AC. DC assumes PF = 1. Typical AC loads are 0.8–0.95.

Current (Amps)

This is the calculated line current based on your inputs.

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How the amperage calculator works

This calculator uses standard electrical formulas to convert your power, voltage and power factor into line current. You choose the current type (DC, single-phase AC, or three-phase AC), set power and voltage, and the tool computes the corresponding current in amps.

DC watts to amps

For direct current circuits the relationship is straightforward: current equals power divided by voltage. Mathematically: I = P ÷ V. If you enter 120 W at 12 V, the result is 10 A.

Single-phase AC amps

In single-phase AC circuits the effective power includes the power factor (PF). The calculator applies: I = P ÷ (V × PF). For example, a 2000 W load on 230 V with PF = 0.8 draws roughly 2000 ÷ (230 × 0.8) ≈ 10.9 A.

Three-phase AC amps

Three-phase systems depend on whether your voltage is line-to-line or line-to-neutral:

Line to line (Δ connection): I = P ÷ (√3 × V × PF).
Line to neutral (Y connection): I = P ÷ (3 × V × PF).

The calculator chooses the correct version based on the “Voltage type” selector when three-phase is selected.

How to use the amperage calculator

Select Current type: DC, AC – Single phase, or AC – Three phase.
Enter the Voltage in volts (RMS). For three-phase, match it to the chosen voltage type.
Enter Power and choose W or kW from the dropdown.
For AC, set a Power factor. For DC, the tool assumes PF = 1 and disables the field.
Optionally adjust Decimals to format the current value for reports or documentation.

Amperage, volts and watts – quick reference

Amperage (current) measures how much charge flows through a conductor per second. Voltage measures electrical potential difference, and power in watts describes how fast electrical energy is being used or delivered.

Core relationships

DC: P = V × I and I = P ÷ V.
Single-phase AC: P = V × I × PF.
Three-phase AC (line-to-line): P = √3 × V × I × PF.
Three-phase AC (line-to-neutral): P = 3 × V × I × PF.

Typical power factor values

Incandescent and resistive heaters: PF ≈ 1.0.
Modern LED lighting with good drivers: PF ≈ 0.9–0.95.
Small induction motors and compressors: PF ≈ 0.75–0.9.

Practical examples

1 kW single-phase load at 230 V, PF = 1 → I ≈ 4.35 A.
3 kW three-phase load at 400 V (line-to-line), PF = 0.8 → I ≈ 5.4 A per phase.
500 W DC load at 24 V → I ≈ 20.8 A.

Safety note

This calculator is for planning and educational purposes. Always follow local electrical codes and consult a qualified electrician when sizing conductors, breakers or protection devices.

FAQs

How do I convert watts to amps?

For DC use I = P ÷ V. For single-phase AC use I = P ÷ (V × PF). For three-phase AC use I = P ÷ (√3 × V × PF) for line-to-line or I = P ÷ (3 × V × PF) for line-to-neutral.

How do I calculate amps in a single-phase AC circuit?

Enter power, voltage and power factor, select “AC – Single phase”, and the tool applies I = P ÷ (V × PF) to give you the current in amps.

How do I calculate amps in a three-phase circuit?

Choose “AC – Three phase”, set voltage type, enter power, voltage and PF. The calculator uses the correct three-phase formula and outputs current per line.

What power factor should I use?

If your equipment datasheet shows PF, enter that value. If not, 0.8 is a reasonable conservative assumption for many inductive loads such as motors.

How many amps is 1 kW at 230 V?

With PF = 1 the current is about 4.35 A (1000 ÷ 230). With PF = 0.8 it is roughly 5.43 A. The calculator can show both by changing the power factor value.

Is this amperage calculator suitable for motor FLA sizing?

It can estimate current from nameplate kW or kW-equivalent watts, voltage and PF, but always compare with manufacturer-rated full-load current for final wiring and protection decisions.