Watts to Amps Converter
Convert watts to amps for DC and AC circuits - enter watts, voltage and power factor.
What this tool does
A watts to amps converter calculates electrical current from power and voltage. For DC circuits, current in amps equals watts divided by volts. For AC single-phase circuits, you also divide by the power factor, which accounts for the phase difference between voltage and current in inductive loads like motors. Enter the watts, the voltage, and whether the circuit is DC or AC, and the calculator gives the current in amps.
Converts power in watts to current in amps for DC circuits using I = P ÷ V.
Converts power in watts to current in amps for AC single-phase circuits using I = P ÷ (V × PF).
Shows the formula used and explains why AC needs power factor.
Lets you toggle between DC and AC modes with the correct formula for each.
How to use it
- Choose whether the circuit is DC or AC.
- Enter the power in watts.
- Enter the voltage in volts.
- For AC circuits, enter the power factor (a value between 0 and 1).
- Read the current in amps.
Why use this calculator
Shows the formula used and explains why AC needs power factor, because the difference between dividing by volts alone and dividing by volts times power factor is the difference between a correct and an incorrect wire size, breaker size or fuse rating. Forgetting power factor on an inductive AC load underestimates the current, which can lead to overheating.
Why we built it
We built the watts to amps converter to support both DC and AC with a clear toggle, because the two cases use different formulas and mixing them up is a common and costly error. The amps to watts converter runs the same calculation in reverse. The volts to watts calculator and the Ohms Law calculator cover the other combinations of voltage, current, resistance and power.
If your task goes further, try the Power Factor Calculator to work out the power factor itself, and the kVA to kW converter for apparent versus real power.
Who this tool is for
- Electricians and electrical students checking circuit loads
- DIYers sizing wires, fuses and breakers for a project
- Solar installers checking DC current from panels or batteries
- Anyone who needs to know how much current a device draws
When to use it
- Sizing a wire, fuse or breaker for a known load.
- Checking whether a circuit can handle an additional appliance.
- Verifying the current rating of a solar panel or battery.
- Converting a device's wattage into the current it will draw from a known supply.
How it is calculated
DC: current in amps = watts ÷ volts. AC single-phase: current in amps = watts ÷ (volts × power factor). Power factor is 1 for purely resistive loads and lower for inductive loads such as motors.
Worked example: a 1,200-watt heater on a 230-volt AC supply with a power factor of 1 (resistive). Current = 1,200 ÷ (230 × 1) = 5.2 amps. A 1,200-watt motor with a power factor of 0.8 on the same supply draws 1,200 ÷ (230 × 0.8) = 6.5 amps - 25% more current for the same power.
For AC three-phase circuits, divide by the square root of 3 as well: I = P ÷ (√3 × V × PF). This calculator covers single-phase only.
What you enter, and what you get back
| Item | Details |
|---|---|
| Circuit type | DC or AC single-phase. |
| Power | The power in watts. |
| Voltage | The supply voltage in volts. |
| Power factor | Between 0 and 1, required for AC. |
| Result | The current in amps. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Current seems too high | Power factor was ignored on an AC inductive load. | Enter the correct power factor. |
| Voltage is not standard | Different countries and systems use different voltages. | Use the actual supply voltage. |
| Watts unknown | Only amps are known. | Use the amps to watts converter instead. |
A worked example
These are the values the calculator opens with, so you can see exactly what it does with them. Change any value on the page and the result updates; the figures below come from the same calculation.
| Input | Value |
|---|---|
| Circuit type | AC single-phase |
| Power | 1200 W |
| Voltage | 230 V |
| Power factor | 0.95 |
With those inputs, the calculator returns:
- Current: 5.5 amps
- Formula used: I = P ÷ (V × PF) = 1200 ÷ (230 × 0.95)
Assumptions and limitations
- Covers DC and AC single-phase only; three-phase requires a different formula.
- Power factor must be known or estimated; a wrong value gives a wrong current.
- Assumes a steady voltage; real supplies can vary.
- An aid for estimation, not a substitute for an electrician's calculation for fixed wiring.
Frequently asked questions
How do I convert watts to amps?
For DC circuits, divide watts by volts: I = P ÷ V. For AC single-phase circuits, divide watts by volts times the power factor: I = P ÷ (V × PF). For example, 1,200 watts at 230 volts DC draws 5.2 amps.
What is the difference between AC and DC current?
DC (direct current) flows in one direction constantly, like from a battery. AC (alternating current) reverses direction many times per second - 50 or 60 times depending on the country - and is what comes from wall sockets. AC allows efficient voltage transformation over long distances.
Why does AC need a power factor?
In AC circuits with inductive loads such as motors, the voltage and current waveforms fall out of phase. The power factor measures how much of the apparent power (volts times amps) is actually doing useful work. A lower power factor means more current is needed for the same real power, so it must be included in the calculation.
What is a typical power factor?
Resistive loads like heaters and incandescent bulbs have a power factor of 1.0. Motors and other inductive loads typically range from 0.7 to 0.95. Modern switch-mode power supplies often have a power factor of 0.6 to 0.9. A value of 0.8 is a reasonable default when the actual power factor is unknown.
How do I find the wattage of an appliance?
Check the label on the appliance, usually on the back or bottom, or the manual. If only amps and voltage are known, multiply them together (and by power factor for AC) to get watts. For a more accurate figure, use a plug-in power meter.
Is this the same as my electricity bill amps?
No. Your electricity bill measures energy in kilowatt-hours over a month, not instantaneous current. The amps shown here is the current the device draws at the moment it is running. The bill's kWh figure depends on that current multiplied by the voltage and the hours of use.