Watts to Amps Calculator (and Amps to Watts)

Convert power to current, or current to power, for DC, single-phase AC and three-phase AC — with the power factor where it belongs and the current every common household appliance draws at 230 V.

Last updated 22 Sep 2026

Watts ⇄ amps

W ⇄ A for DC, 1-phase and 3-phase

What do you want?The other box is locked and shows the answer, so switching direction starts from the same load.

System

Power (W)

Current (A)For three-phase, the line current — the current in one of the three lines.

Voltage (V)230 V in India, the Gulf and Europe, 120 V in North America; for three-phase the line-to-line voltage (400 V, 415 V, 208 V or 480 V).

Power factor1.0 for heaters, kettles, geysers, filament lamps and anything purely resistive; about 0.8 for motors and pumps, 0.5–0.9 for LED drivers and electronics unless corrected. DC has no power factor, so the box locks at 1.

The load as the page treats it: a DC supply, a single-phase line and neutral, or three lines feeding a balanced star load. The ammeter reads the current the page calculates — for three-phase, the current in one line. On AC the dots show the size of each RMS current and the direction drawn is a convention, because the current reverses 100 or 120 times a second; on DC it really does flow that way.

10AExample

2,300 W on a 230 V single-phase supply at unity power factor (a 2.3 kW geyser)

Power and current

DC: I = P ÷ V 1-phase: I = P ÷ (V × PF) 3-phase: I = P ÷ (√3 × V_LL × PF)

P: real power in watts — the power that does work and that the meter bills
V: RMS voltage; for three-phase, the line-to-line voltage
PF: power factor, cos φ for a sinusoidal supply: 1 for resistive loads
√3: 1.732…, because the three phases are 120° apart

Worked example

2,300 W on a 230 V single-phase supply at unity power factor (a 2.3 kW geyser)
I = P ÷ (V × PF) = 2,300 ÷ (230 × 1) = 10 A
Apparent power = 230 × 10 = 2,300 VA — at unity power factor watts and volt-amperes are the same number
The same 2,300 W on a 415 V three-phase supply would be 2,300 ÷ (1.732 × 415 × 1) = 3.20 A per line
A 900 W pump at PF 0.8 draws 900 ÷ (230 × 0.8) = 4.89 A, not the 3.91 A the watts alone suggest

What common appliances draw (resistive loads, unity power factor)

Typical nameplate powers; read your own rating plate. Motors, pumps, compressors and cheap LED drivers have a power factor below 1, so they draw more current than these figures — divide again by the power factor.
Appliance	Typical power	At 230 V	At 120 V
LED bulb	9 W	0.04 A	0.07 A
Ceiling fan	75 W	0.33 A	0.62 A
Television, 43 inch	100 W	0.43 A	0.83 A
Refrigerator (running)	150 W	0.65 A	1.25 A
Washing machine	500 W	2.17 A	4.17 A
Microwave oven	1,200 W	5.22 A	10.00 A
Electric iron	1,000 W	4.35 A	8.33 A
1.5 ton air conditioner	1,500 W	6.52 A	12.50 A
Water heater (geyser)	2,000 W	8.70 A	16.67 A
Electric kettle	2,200 W	9.57 A	18.33 A
1 HP water pump (input)	900 W	3.91 A	7.50 A
Induction cooktop	2,000 W	8.70 A	16.67 A

Converting watts to amps, and back

Watts are power; amps are current. They are connected by the voltage, and on AC by the power factor as well. For direct current the rule is simply I = P ÷ V: a 60 W bulb on a 12 V battery draws 5 A. For single-phase AC the current is I = P ÷ (V × PF), and for a balanced three-phase load the line current is I = P ÷ (√3 × V_LL × PF), with V_LL the voltage between two lines.

Why the power factor is in there. In an AC circuit with motors, transformers or electronic supplies, current and voltage do not peak at the same instant. The product of RMS volts and RMS amps is the apparent power in volt-amperes; only part of it, VA × PF, does useful work and registers on an energy meter. The cable, the switch and the breaker carry the whole current regardless. A 900 W pump at a power factor of 0.8 draws 4.89 A at 230 V, not the 3.91 A that the watts alone imply — a 25% difference, which is exactly the margin that decides whether a 6 A or a 10 A breaker is right.

Three-phase halves the current twice over. The same 2,300 W drawn from a 415 V three-phase supply is only 3.20 A in each line, against 10 A on single-phase 230 V. That is why workshops, lifts, large air conditioners and any load above roughly 5 kW are wired three-phase: thinner cables, smaller breakers and, for motors, a much better starting characteristic.

Use the current, not the watts. Cable size, breaker rating and voltage drop all follow the current. Convert the load here, then size the cable with the wire size calculator, check the drop with the voltage drop calculator, and pick the protective device with the MCB size calculator. For the relationship between kVA and kW on generators and UPS units, see the kVA to kW calculator; to see what all these loads cost over a month, the electricity consumption calculator.

Frequently asked questions

How many amps is 1000 watts at 230 V?

At unity power factor, 1,000 ÷ 230 = 4.35 A. At a power factor of 0.8 it is 5.43 A. On a 120 V supply the same 1,000 W is 8.33 A.

How do I convert amps to watts?

Multiply: DC watts = A × V; single-phase AC watts = A × V × PF; three-phase watts = √3 × A × V_LL × PF. Switch this page to “amps → watts” and it does it for you.

Do I use 230 V or 400 V for a three-phase load?

The line-to-line voltage — 400 V or 415 V — with the √3 in the formula. The 230 V (or 240 V) figure is the phase voltage, line to neutral, which is what single-phase loads in the same installation see.

What power factor should I assume?

1.0 for heating elements, kettles, geysers and filament lamps. About 0.8 for induction motors, pumps and compressors at full load, lower when lightly loaded. Electronic loads vary: equipment with power-factor correction reaches 0.95 or better, cheap drivers can be near 0.5. If the rating plate gives both watts and amps, divide to find the real figure.

Why does my meter show fewer units than the amps suggest?

Domestic meters count real power (kWh), not apparent power. A load with a poor power factor draws current that flows out and back without doing work; you pay for it in cable heating, not in units — though industrial tariffs usually add a penalty for it.

Related calculators

References

Hughes E, Hiley J, Brown K, Smith I M. Electrical and Electronic Technology, 12th ed. Pearson 2016: three-phase star and delta relationships, the power triangle and power-factor improvement.
IEC 60038:2009, IEC standard voltages: 230/400 V is the standard low-voltage three-phase system.
IEC 60364-4-43:2008, Low-voltage electrical installations — Protection against overcurrent, clause 433.1: I_B ≤ I_n ≤ I_Z and I₂ ≤ 1.45 × I_Z.