Watts to Amps Calculator (DC, AC & Three-Phase)

Convert watts to amps for DC, single-phase or three-phase AC: enter the wattage and voltage to get the current, or solve watts or volts from amps.

Solve for

Power means useful output. At the default 100% efficiency, output power equals input electrical real power.

Electrical system

Useful output power

Voltage (V; RMS line-to-line for three-phase)

AC power factor (0 to 1)

Typical value 1 for heaters, kettles and incandescent lights; motors and some electronics are lower (about 0.8–0.95).

Efficiency and current allowance

Input-to-output efficiency (%)

Default 100% makes output equal real electrical input. For useful motor/output power, enter the corresponding efficiency.

Current allowance (% of rating)

Default 80% is an editable arithmetic assumption; it does not select a circuit breaker or conductor.

Watts ↔ Amps Conversion Table (DC, V = 220 V)
Watts to Amps	Amps to Watts
5 watts = 0.023 amps	0.1 amps = 22 watts
10 watts = 0.045 amps	0.2 amps = 44 watts
20 watts = 0.091 amps	0.25 amps = 55 watts
25 watts = 0.114 amps	0.5 amps = 110 watts
30 watts = 0.136 amps	0.75 amps = 165 watts
40 watts = 0.182 amps	1 amp = 220 watts
50 watts = 0.227 amps	1.5 amps = 330 watts
60 watts = 0.273 amps	2 amps = 440 watts
75 watts = 0.341 amps	3 amps = 660 watts
100 watts = 0.455 amps	4 amps = 880 watts
150 watts = 0.682 amps	5 amps = 1100 watts
200 watts = 0.909 amps	6 amps = 1320 watts
250 watts = 1.136 amps	7.5 amps = 1650 watts
300 watts = 1.364 amps	10 amps = 2200 watts
400 watts = 1.818 amps	12 amps = 2640 watts
500 watts = 2.273 amps	15 amps = 3300 watts
750 watts = 3.409 amps	16 amps = 3520 watts
1000 watts = 4.545 amps	20 amps = 4400 watts
1500 watts = 6.818 amps	30 amps = 6600 watts
2000 watts = 9.091 amps	50 amps = 11000 watts
Formulas: I = P ÷ V and P = I × V. This table uses real electrical input watts, DC (or single-phase AC with PF = 1), V = 220 V and interface efficiency 100%.

Calculator Operations	Required Inputs
Convert Watts to Amps	Useful output watts, voltage, electrical system; true PF for AC; optional efficiency
Convert Amps to Watts	Amps, voltage, electrical system; true PF for AC; optional efficiency
Solve Voltage	Useful output watts, amps, electrical system; true PF for AC; optional efficiency

Watts to Amps Formula

The equations below use real electrical input power P. At the interface default of 100% efficiency, useful output power equals input power. For a lower entered efficiency fraction eta, input power equals useful output divided by eta.

For DC Currents: I = P / V

Where I is the current (amps)
P is the power in watts
V is the voltage in volts

For single-phase AC: I = P / (V * PF). For balanced three-phase AC: line current I = total P / (√(3) * VLL * PF), using RMS line-to-line voltage VLL.

Where I is the current (amps)
P is the power in watts
V is the voltage in volts
PF is the power factor.

DC hides and ignores power factor. True AC power factor is real electrical input power divided by apparent power; it is distinct from conversion efficiency. Watts measure power and amps measure current, so voltage and the appropriate system assumptions are also needed. The optional 80% allowance reports current divided by 0.80 and can be changed; it does not select a circuit rating or establish code compliance. Sensitivity holds the other entered quantities fixed.

watts to amps formula — These reference equations use real electrical input watts; the AC equation shown is single-phase. Balanced three-phase AC also includes √(3), and useful output power requires the separate efficiency adjustment described above.