Free electrical calculator for DC, 1-phase and 3-phase

Watts to Amps Calculator

This watts to amps calculator converts power to current, or amps back to watts, for DC, single-phase and three-phase circuits. Add the power factor or motor horsepower and instantly see the right breaker size, how loaded your circuit is and the full working.

Watts ⇄ Amps
W, kW and HP
Power factor
Breaker sizing
Live chart

Watts to amps converter

Your custom conversion chart

Follows the voltage, circuit type and power factor you set above.

Watts to amps at 120 V, AC single-phase, PF 1.00
Power	Current	Breaker (125%)
100 W	0.833 A	15 A
200 W	1.67 A	15 A
300 W	2.5 A	15 A
500 W	4.17 A	15 A
750 W	6.25 A	15 A
1,000 W	8.33 A	15 A
1,200 W	10 A	15 A
1,500 W	12.5 A	20 A
1,800 W	15 A	20 A
2,000 W	16.67 A	25 A
2,500 W	20.83 A	30 A
3,000 W	25 A	35 A
4,000 W	33.33 A	45 A
5,000 W	41.67 A	60 A
7,500 W	62.5 A	80 A
10 kW	83.33 A	110 A

Formulas

Watts to Amps Formulas for DC, AC and Three-Phase

Current depends on three things: the power of the load, the supply voltage and, for AC, the power factor. Pick the formula that matches your circuit. Every example below can be checked with the calculator above.

DC watts to amps

I (A) = P (W) ÷ V (V)

Batteries, solar panels, RVs, boats and car electronics run on DC. A 300 W fridge on a 12 V battery draws 300 ÷ 12 = 25 A.

AC single-phase watts to amps

I = P ÷ (V × PF)

Home outlets are single-phase: 120 V in North America and 230 V in most other countries. A 1,500 W load at 230 V with a power factor of 0.95 draws 1,500 ÷ (230 × 0.95) = 6.86 A.

Three-phase watts to amps (line to line)

I = P ÷ (√3 × V(LL) × PF)

Use this with the voltage between two phases, such as 208 V, 400 V or 480 V. A 10 kW motor load at 400 V and PF 0.85 draws 10,000 ÷ (1.732 × 400 × 0.85) = 16.98 A per line.

Three-phase watts to amps (line to neutral)

I = P ÷ (3 × V(LN) × PF)

Use this with the phase to neutral voltage, such as 230 V or 277 V. The same 10 kW load at 230 V and PF 0.85 draws 10,000 ÷ (3 × 230 × 0.85) = 17.05 A per line.

Need amps to watts instead? Rearrange the same formulas: P = V × I for DC, P = V × I × PF for single-phase and P = √3 × V × I × PF for three-phase. For example, a 20 A circuit at 240 V carries up to 4,800 W. For resistance and voltage problems, try the Ohm’s law calculator.

Reference

Watts to Amps Conversion Chart

Amps for common wattages at the most used voltages, assuming a resistive load (power factor 1). For motors, compressors and other inductive loads, divide each value by the power factor, or set it in the calculator for an exact answer.

Watts to amps chart at common voltages (power factor 1)
Watts	12 V DC	24 V DC	120 V	230 V	240 V	400 V 3-phase	480 V 3-phase
100 W	8.33 A	4.17 A	0.83 A	0.43 A	0.42 A	0.14 A	0.12 A
200 W	16.67 A	8.33 A	1.67 A	0.87 A	0.83 A	0.29 A	0.24 A
300 W	25.00 A	12.50 A	2.50 A	1.30 A	1.25 A	0.43 A	0.36 A
500 W	41.67 A	20.83 A	4.17 A	2.17 A	2.08 A	0.72 A	0.60 A
750 W	62.50 A	31.25 A	6.25 A	3.26 A	3.13 A	1.08 A	0.90 A
1,000 W	83.33 A	41.67 A	8.33 A	4.35 A	4.17 A	1.44 A	1.20 A
1,200 W	100.0 A	50.00 A	10.00 A	5.22 A	5.00 A	1.73 A	1.44 A
1,500 W	125.0 A	62.50 A	12.50 A	6.52 A	6.25 A	2.17 A	1.80 A
1,800 W	150.0 A	75.00 A	15.00 A	7.83 A	7.50 A	2.60 A	2.17 A
2,000 W	166.7 A	83.33 A	16.67 A	8.70 A	8.33 A	2.89 A	2.41 A
2,500 W	208.3 A	104.2 A	20.83 A	10.87 A	10.42 A	3.61 A	3.01 A
3,000 W	250.0 A	125.0 A	25.00 A	13.04 A	12.50 A	4.33 A	3.61 A
3,500 W	291.7 A	145.8 A	29.17 A	15.22 A	14.58 A	5.05 A	4.21 A
4,000 W	333.3 A	166.7 A	33.33 A	17.39 A	16.67 A	5.77 A	4.81 A
5,000 W	416.7 A	208.3 A	41.67 A	21.74 A	20.83 A	7.22 A	6.01 A
6,000 W	500.0 A	250.0 A	50.00 A	26.09 A	25.00 A	8.66 A	7.22 A
7,500 W	625.0 A	312.5 A	62.50 A	32.61 A	31.25 A	10.83 A	9.02 A
10,000 W	833.3 A	416.7 A	83.33 A	43.48 A	41.67 A	14.43 A	12.03 A

Appliances

How Many Amps Do Common Appliances Use?

Typical running wattage and current for everyday appliances. Your device label gives the exact rating, and motors or compressors can briefly draw 3 to 7 times more current at start-up. To see what these loads cost to run, use the electricity cost calculator.

Typical running watts and amps for household appliances (power factor 1)
Appliance	Typical watts	Amps at 120 V	Amps at 230 V	Amps at 240 V
LED bulb	10 W	0.08 A	0.04 A	0.04 A
Laptop charger	65 W	0.54 A	0.28 A	0.27 A
Ceiling fan	75 W	0.63 A	0.33 A	0.31 A
55-inch LED TV	100 W	0.83 A	0.43 A	0.42 A
Refrigerator (running)	150 W	1.25 A	0.65 A	0.63 A
Desktop PC	300 W	2.50 A	1.30 A	1.25 A
Washing machine	500 W	4.17 A	2.17 A	2.08 A
Microwave oven	1,000 W	8.33 A	4.35 A	4.17 A
Toaster	1,200 W	10.00 A	5.22 A	5.00 A
Space heater	1,500 W	12.50 A	6.52 A	6.25 A
Air conditioner (1.5 ton)	1,700 W	14.17 A	7.39 A	7.08 A
Hair dryer	1,800 W	15.00 A	7.83 A	7.50 A
Electric kettle	2,000 W	16.67 A	8.70 A	8.33 A
Water heater (tank)	4,500 W	37.50 A	19.57 A	18.75 A
Clothes dryer	5,000 W	41.67 A	21.74 A	20.83 A
Level 2 EV charger	7,200 W	60.00 A	31.30 A	30.00 A

Why ours

Why This Watts to Amps Calculator Is Better

Most converters stop at one formula and one direction. This one covers the questions you actually have when planning a circuit.

Both directions in one place

Switch between watts to amps and amps to watts without opening another page. Enter power in W, kW or HP and current in A or mA.

Every circuit type

DC, AC single-phase and AC three-phase, with a clear choice between line to line and line to neutral voltage so the √3 factor is never misapplied.

Real power factor support

Use the slider or presets for resistive, LED and motor loads. You also get apparent power in kVA and reactive power in kVAR.

Breaker size and load meter

See the next standard NEC or IEC breaker at 125% of the load, then check what share of a 15 A, 16 A or larger circuit you are using.

Shows the working

Each result lists the formula with your numbers plugged in, so you can verify it, learn from it or paste it into a report.

Private, fast and shareable

Runs entirely in your browser with no sign-up and no tracking of your inputs. Copy the answer or share a link that reopens the same calculation.

Guide

How to Use the Watts to Amps Calculator

Getting an answer takes a few seconds. Results update as you type, so you can try different voltages or loads instantly.

Choose the direction
Select Watts → Amps to find current, or Amps → Watts to find power.
Select the circuit type
Pick DC for batteries and solar, AC 1-phase for home outlets, or AC 3-phase for commercial and industrial supplies.
Enter the power and voltage
Type the wattage or tap an appliance, then choose a voltage chip. For motors, switch the unit to HP and add the efficiency.
Set the power factor
Keep 1.00 for heaters, kettles and incandescent lights. Use 0.85 for a typical motor when the nameplate does not list it.
Read and share the result
Check the amps, kVA, suggested breaker and circuit load meter. Copy the result or share a link in one tap.

Benefits

Who Benefits From Converting Watts to Amps

Knowing the current a load draws keeps circuits safe, prevents nuisance trips and helps you buy the right cable, fuse or inverter.

Homeowners and renters

Find out whether a space heater, kettle and microwave can share one circuit before the breaker trips, and plan where new appliances should go.

Electricians and contractors

Run quick single-phase and three-phase load checks on site, with breaker sizes for both US and IEC panels and a working you can show the client.

Solar, RV and van builders

Size 12 V, 24 V and 48 V cables, fuses and inverters from appliance wattage, then check cable losses with the voltage drop calculator.

Students and engineers

See exactly how power factor, apparent power and the √3 factor change the answer, with the formula shown for every single result.

Real world

Why Your Measured Amps May Differ

A clamp meter reading rarely matches watts ÷ volts exactly. These are the usual reasons.

Power factor. Motors, compressors and some older lighting draw more current than their watt rating suggests, because part of the current does no useful work.
Start-up surge. Fridges, air conditioners and pumps can pull several times their running current for a moment, which is why breakers have time-delay curves.
Voltage variation. Supply voltage often sits a few percent above or below nominal, and constant-power loads draw more current when the voltage drops.
Inverter losses. A 1,000 W load on a 12 V inverter pulls about 90 to 95 A from the battery, not 83 A, because inverters are roughly 88 to 93% efficient.

FAQ

Watts to Amps FAQ

How many amps is 1000 watts?

It depends on the voltage. 1,000 watts draws 8.33 amps at 120 V, 4.35 amps at 230 V, 4.17 amps at 240 V and 83.3 amps at 12 V DC, assuming a power factor of 1.

How do you convert watts to amps?

For DC, divide watts by volts: I = P ÷ V. For AC single-phase, divide by volts times power factor: I = P ÷ (V × PF). For three-phase, use I = P ÷ (1.732 × V × PF) with the line to line voltage.

How many watts can a 15 amp circuit handle?

A 15 A circuit at 120 V can carry 1,800 W at most, but continuous loads should stay under 80%, which is 1,440 W. A 20 A circuit at 120 V handles 2,400 W peak and 1,920 W continuous.

How many amps does a 1500 watt heater use?

A 1,500 W space heater draws 12.5 A at 120 V, 6.52 A at 230 V and 6.25 A at 240 V. On a 120 V, 15 A circuit that is 83% of the rating, so avoid running other large loads on the same circuit.

Can you convert watts to amps without the voltage?

No. Current depends on voltage, so the same 1,000 W load draws twice as much current at 120 V as it does at 240 V. Check the appliance label or your supply voltage first.

What power factor should I use?

Use 1.0 for resistive loads such as heaters, kettles and incandescent bulbs. LED drivers and electronics with power factor correction are usually 0.9 to 0.99. Induction motors typically run at 0.75 to 0.9, so 0.8 is a safe estimate when the nameplate does not say.

How do you calculate three-phase amps from kW?

Multiply kW by 1,000, then divide by 1.732 × line to line voltage × power factor. For example, 10 kW at 400 V with a power factor of 0.85 draws 10,000 ÷ (1.732 × 400 × 0.85) = 16.98 A per line.

How many amps does a 12V 100W device draw?

A 100 W device on 12 V DC draws 100 ÷ 12 = 8.33 A. If it runs through an inverter from a 12 V battery, add about 10% for inverter losses and plan for roughly 9.2 A.

Size Every Circuit With Confidence

Use the watts to amps calculator whenever you add an appliance, plan a new circuit or wire a solar or RV system. Then check cable losses, running costs and cooling loads with our related tools.

Calculate amps now

Results are estimates for planning. Always follow your local electrical code and use a licensed electrician for installation work.