🔌 Watts to Amps Converter: Convert Power to Current Instantly
By Shihab Mia · Updated 2026-07-31
Convert between watts and amps using amps = watts / volts. Add a power factor for AC motors and other inductive loads; leave it at 1.0 for resistive or DC loads.
1.0 for resistive/DC loads. 0.8 to 0.95 typical for motors and other inductive AC loads.
| Watts | Amps at 120 V | Amps at 240 V |
|---|
This watts to amps converter uses the formula Amps = Watts / Volts, so a 1500 watt heater on a 120 volt circuit draws 12.5 amps. Enter any two of watts, volts, and (for AC motors) power factor, and the calculator returns the current instantly, with a reverse Amps to Watts mode built in for the opposite conversion. It handles both resistive loads, where power factor is 1.0, and inductive AC loads like motors and pumps, where a power factor of 0.8 to 0.95 is typical.
What is the Watts to Amps Converter?
Converting watts to amps means finding how much electrical current a device draws for a given amount of power at a known voltage. The relationship comes directly from the power formula P = V x I, which rearranges to give the core watts to amps formula: Amps = Watts / Volts. This works exactly for direct current and for purely resistive AC loads such as space heaters, incandescent bulbs, kettles, and toasters, where the voltage and current are perfectly in phase and all the delivered power does useful work.
AC circuits with inductive components, like motors, compressors, pumps, and transformers, complicate the picture slightly because voltage and current fall out of phase. In these cases the simple watts to amps converter math needs a power factor (PF) term: Amps = Watts / (Volts x Power Factor). Power factor is a number between 0 and 1 describing how efficiently the current is being converted into real work; a resistive heater has a power factor of 1.0, while a typical induction motor runs at 0.8 to 0.95. Skipping the power factor on a motor load will understate the true amp draw, which matters when sizing wiring, breakers, and extension cords.
The amps to watts converter runs the same equation in reverse: Watts = Amps x Volts x Power Factor. This direction is useful when you know a device nameplate current rating (many older appliances and tools list amps rather than watts) and need the equivalent power to size a generator, inverter, or UPS. Multiplying amps by volts alone, without the power factor, gives apparent power in volt-amps (VA) rather than real power in watts; for resistive loads VA and watts are identical since PF is 1, but for motors the two numbers diverge.
Voltage matters enormously in any watts to amps conversion because current and voltage are inversely related for a fixed wattage. A 1500 watt load draws 12.5 amps at 120 volts (the standard US household outlet) but only 6.25 amps at 240 volts (common for US dryers, ranges, and most of Europe and Asia). This is precisely why higher-voltage regions and industrial three-phase 208 volt systems can use thinner wire gauges for the same power delivery: less current means less resistive heating in the conductor for the same load.
When to use it
- Sizing the correct wire gauge and breaker for an appliance, given its wattage and outlet voltage.
- Checking whether a generator, inverter, or UPS can supply enough current for a listed wattage.
- Converting a motor or pump nameplate wattage into amps, accounting for a realistic power factor.
- Working out amp draw when switching a device between 120 V and 240 V supplies, or comparing US and international voltages.
How to use the Watts to Amps Converter
- Stay on the "Watts to Amps" tab (or switch to "Amps to Watts" for the reverse calculation).
- Enter the power in watts (default 1500 W) and pick the supply voltage from the preset list, or choose Custom to type your own.
- Leave Power Factor at 1.0 for resistive or DC loads; for AC motors and inductive loads, enter a realistic value between 0.8 and 0.95.
- Read the current in amps update live, then use Copy Result to save the figure.
Formula & method
Worked examples
Find the current draw of a 1500 watt space heater plugged into a standard 120 volt US outlet (resistive load, power factor 1.0).
- Use the primary formula: Amps = Watts / Volts
- Substitute the values: Amps = 1500 / 120
- Divide: Amps = 12.5
- Since the heater is a resistive load, no power factor adjustment is needed
Result: The heater draws 12.5 amps.
Find the power drawn by an AC induction motor pulling 12 amps at 240 volts with a power factor of 0.85, typical for an inductive motor load.
- Use the reverse formula: Watts = Amps x Volts x Power Factor
- Substitute the values: Watts = 12 x 240 x 0.85
- Multiply the current and voltage first: 12 x 240 = 2880
- Multiply by the power factor: 2880 x 0.85 = 2448
Result: The motor draws 2448 watts (2.448 kW) of real power, even though the apparent power (volts x amps, ignoring power factor) is 2880 VA.
Common wattages converted to amps at 120 V and 240 V (resistive load, power factor 1.0)
| Watts | Amps at 120 V | Amps at 240 V |
|---|---|---|
| 100 W | 0.83 A | 0.42 A |
| 300 W | 2.5 A | 1.25 A |
| 500 W | 4.17 A | 2.08 A |
| 750 W | 6.25 A | 3.13 A |
| 1000 W | 8.33 A | 4.17 A |
| 1200 W | 10 A | 5 A |
| 1500 W | 12.5 A | 6.25 A |
| 1800 W | 15 A | 7.5 A |
| 2000 W | 16.67 A | 8.33 A |
| 3000 W | 25 A | 12.5 A |
| 5000 W | 41.67 A | 20.83 A |
Amps drawn by a fixed 1500 W load at common supply voltages
| Voltage | Typical use | Amps at 1500 W |
|---|---|---|
| 12 V | Cars, boats, RV and solar DC systems | 125 A |
| 110 V | Older US and Japan appliance ratings | 13.64 A |
| 115 V | US small appliance nominal rating | 13.04 A |
| 120 V | Standard US and Canada household outlet | 12.5 A |
| 208 V | US commercial three-phase circuits | 7.21 A |
| 220 V | Older Europe/Asia wiring, some US dryers | 6.82 A |
| 230 V | UK and Europe standard household supply | 6.52 A |
| 240 V | US large appliances, ranges, dryers | 6.25 A |
Common mistakes to avoid
- Forgetting the power factor on AC motor loads. Using Amps = Watts / Volts alone on a motor, pump, or compressor understates the real current draw. Inductive loads need Amps = Watts / (Volts x Power Factor), with PF typically 0.8 to 0.95, not 1.0.
- Confusing nameplate watts with nameplate VA. Some equipment labels list volt-amps (VA) instead of watts. For resistive loads VA equals watts, but for motors VA is higher than real watts because VA ignores power factor.
- Using the wrong regional voltage. Plugging in 120 V by default when a device actually runs on 230 V (or vice versa) doubles or halves the calculated amps. Always match the voltage field to the actual supply.
- Ignoring the difference between running amps and startup amps. A watts to amps conversion gives steady-state running current. Motors, compressors, and pumps can briefly draw 3 to 7 times their running amps at startup, which matters for breaker and wire sizing.
Glossary
- Watt (W)
- The unit of electrical power, equal to one joule of energy per second. It is the rate at which a device consumes or delivers energy.
- Ampere (A)
- The unit of electric current, often shortened to "amp". One ampere is one coulomb of charge flowing per second.
- Volt (V)
- The unit of electrical potential difference, the "push" that drives current through a circuit.
- Power factor (PF)
- A number from 0 to 1 describing how much of the apparent power (volts x amps) is converted into real work. Resistive loads have PF = 1.0; motors and other inductive loads are typically 0.8 to 0.95.
- Apparent power (VA)
- The product of volts and amps without accounting for power factor, measured in volt-amps. Equals real watts only when power factor is 1.0.
- Resistive load
- A device, like a heater or incandescent bulb, where voltage and current stay in phase, so power factor is 1.0 and watts equal volt-amps exactly.
Frequently asked questions
How do I convert watts to amps?
Divide the wattage by the voltage: Amps = Watts / Volts. A 1500 watt appliance on a 120 volt circuit draws 1500 / 120 = 12.5 amps. For AC motors, divide by voltage times power factor instead.
How many amps is 1500 watts?
At 120 volts, 1500 watts equals 12.5 amps (1500 / 120). At 240 volts, the same 1500 watts is only 6.25 amps, since current drops as voltage rises for a fixed wattage.
What is the formula for watts to amps?
The formula is Amps = Watts / Volts for DC and resistive AC loads. For AC loads with a power factor other than 1, use Amps = Watts / (Volts x Power Factor), where PF is typically 0.8 to 0.95 for motors.
How do I convert amps to watts?
Multiply amps by volts (and by power factor for AC motors): Watts = Amps x Volts x Power Factor. For example, 15 amps at 120 volts with PF 1.0 equals 1800 watts.
Why does the same wattage draw fewer amps at 240 volts than at 120 volts?
Because power equals volts times amps, current is inversely proportional to voltage for a fixed wattage. Doubling the voltage from 120 V to 240 V halves the current needed to deliver the same watts.
What power factor should I use for a motor?
Most single-phase induction motors run at a power factor between 0.8 and 0.95 under normal load; if the exact value is unknown, 0.85 is a reasonable estimate. Resistive loads like heaters always use 1.0.