Watts to Amps Calculator

Convert watts to amps (or reverse amps to watts) with voltage, phase, and power factor—instant bidirectional W ↔ A for appliances, heaters, and AC feeder pre-checks.

Calculator

Quick: watts + voltage → amps. Advanced: reverse direction, three-phase √3, and adjustable PF.

Conversion direction

Real power (W) Example: 1800 W heater. For kW, enter watts (10 kW = 10000).

Voltage (V)

Three-phase: use line-to-line voltage.

Power factor (PF) Resistive ≈ 1.0; motors/UPS often 0.80–0.95.

Phase

Single Phase Three Phase

About this calculator

This watts to amps calculator converts real power (W) to line current (A) using voltage, phase, and PF. It is not a kVA→amps converter—use kVA to Amps when apparent power is known. For √3 teaching and three-phase worked examples, see the 3-Phase Power Calculator. Browse the power calculator hub.

Calculation Results

≈ 15 A (1.800 kW real power)

1800 W · 120 V · PF 1 · Single Phase

Formula: I = W ÷ (V × PF)

Balanced-load estimate from real power. Harmonics, motor starting, and continuous-load 125% breaker margins are not applied here.

Continue Your Calculation

Have line current from watts? Continue to breaker frame screening (link updates from your result).

Breaker size →

Watts to amps quick reference (PF 1.0)

Single-phase resistive: I = W ÷ V. Click a row to load the calculator.

Power	Voltage	Current
	120 V 1φ	8.33 A
	120 V 1φ	15 A
	240 V 1φ	12.5 A
	240 V 1φ	20.8 A
	480 V 3φ PF 0.85	≈ 14.15 A
	120 V 1φ	2400 W

Watts to amps formula

Single-phase: I = W ÷ (V × PF) · W = V × I × PF

Three-phase: I = W ÷ (V × √3 × PF) · W = V × I × √3 × PF

W — real power (watts)
V — RMS voltage (line-to-line for 3φ)
PF — power factor (0–1)
I — line current (amps)

Example: 1800 W ÷ (120 V × 1.0) = 15 A.

Need kW ↔ kVA first? kW to kVA calculator. Need apparent-power amps? kVA to Amps.

When to use which power tool

Goal	Tool
Convert watts ↔ amps (real power)	This page
Convert kVA ↔ amps (apparent power)	kVA to Amps
Convert kW ↔ kVA with PF	kW to kVA
Three-phase kW/kVA from V·A·PF	3-Phase Power
Pick breaker frame from amps	Breaker Size

Frequently Asked Questions

How do I convert watts to amps?

Single-phase: I = W ÷ (V × PF). Three-phase: I = W ÷ (V × √3 × PF). Example: 1800 W at 120 V PF 1.0 = 15 A.

How do I convert amps to watts?

Single-phase: W = V × I × PF. Three-phase: W = V × I × √3 × PF. Example: 15 A at 120 V PF 1.0 = 1800 W.

Do I need power factor for watts to amps?

Yes for AC real power. Resistive loads can use PF ≈ 1.0. Motors and UPS loads often use 0.8–0.95. If you already know kVA, use kVA to Amps instead.

What is 1000 watts in amps at 120V?

At 120 V single-phase PF 1.0: ≈ 8.33 A. At PF 0.9: ≈ 9.26 A. Use the 1000 W preset above.

Is watts to amps the same as kVA to amps?

No. Watts need PF; kVA does not. This page owns W↔A; kVA to Amps owns apparent-power current.