Watts to Amps Calculator
Convert between watts and amps at any voltage — switch direction below, or use the 120V and 12V presets for a standard US outlet or a power station's DC port.
The Formula
Watts, volts, and amps are related by a single fixed equation — Ohm's law applied to power. Once you know any two, you can always find the third.
AC Circuits: Power Factor and Three-Phase
The basic formula assumes a power factor of 1, which is accurate for heaters and lights. Motors and compressors (fridges, pumps, air conditioners) have a power factor below 1, so they draw more amps than watts ÷ volts suggests.
Example: a 1,000W motor at 120V with a power factor of 0.8 draws 1,000 ÷ (120 × 0.8) = 10.4A, not 8.3A. DC loads (12V ports, solar) have no power factor.
Watts to Amps Conversion Chart
Amps = watts ÷ volts, rounded.
| Watts | 12V DC | 120V | 240V |
|---|---|---|---|
| 10W | 0.83A | 0.08A | 0.04A |
| 40W | 3.33A | 0.33A | 0.17A |
| 60W | 5.00A | 0.50A | 0.25A |
| 100W | 8.33A | 0.83A | 0.42A |
| 150W | 12.5A | 1.25A | 0.63A |
| 300W | 25.0A | 2.50A | 1.25A |
| 500W | 41.7A | 4.17A | 2.08A |
| 750W | 62.5A | 6.25A | 3.13A |
| 1,000W | 83.3A | 8.33A | 4.17A |
| 1,200W | 100A | 10.0A | 5.00A |
| 1,500W | 125A | 12.5A | 6.25A |
| 1,800W | 150A | 15.0A | 7.50A |
| 2,000W | 167A | 16.7A | 8.33A |
| 2,400W | 200A | 20.0A | 10.0A |
| 3,000W | 250A | 25.0A | 12.5A |
| 3,600W | 300A | 30.0A | 15.0A |
How Many Watts Can a Circuit Carry?
Watts = volts × amps. For loads that run continuously (3 hours or more), a common guideline is to stay at 80% of the breaker rating. Confirm with your local electrical code.
| Circuit | Maximum watts | Continuous (80%) |
|---|---|---|
| 15A circuit (120V) | 1,800W | 1,440W |
| 20A circuit (120V) | 2,400W | 1,920W |
| 30A circuit (120V), such as an RV TT-30 | 3,600W | 2,880W |
| 30A circuit (240V) | 7,200W | 5,760W |
The same math applies to a power station: a 2,400W inverter can supply 20A at 120V, and a TT-30 RV outlet is rated 30A (see our ports guide).
When You'd Need This Conversion
- Sizing a circuit breaker, extension cord, or fuse for a known wattage load.
- Checking whether a 12V DC accessory (car port, solar input) will overload its rated amperage.
- Comparing a device's amp draw against what an outlet or power strip is rated for.
- Converting a spec sheet that only lists amps into watts you can compare against a power station's output rating.
Sizing a power station instead of an outlet or circuit? Our runtime calculator and ports explained guide are the more direct tools for that. Want the formula explained with worked examples and circuit safety context instead of just the number? See our amps to watts conversion guide.
Frequently Asked Questions
How many amps is 1,000 watts?
At 120V, 1,000 watts is 8.33 amps (1,000 ÷ 120). At 12V it is 83.3 amps, and at 240V it is 4.17 amps. The higher the voltage, the fewer amps for the same watts.
How do I convert watts to amps?
Divide watts by volts: amps = watts ÷ volts. For example, a 1,500W space heater on a 120V outlet draws 1,500 ÷ 120 = 12.5 amps. For AC devices with motors, also divide by the power factor (often 0.8 to 1).
How many watts can a 15 amp or 20 amp circuit handle?
A 15A circuit at 120V can deliver up to 1,800W and a 20A circuit up to 2,400W, but for loads that run continuously (3 hours or more) the common 80% guideline limits you to 1,440W and 1,920W. Check your local electrical code and breaker label.
What voltage should I use for a standard US wall outlet?
120V is the standard for residential US wall outlets. Large appliances on a dedicated circuit (some dryers, ranges) may use 240V — check your specific outlet or breaker rating if you're unsure.
Why does my device's actual amp draw seem higher than this calculation?
This calculator uses the basic P = V × I formula, which assumes 100% power factor. Some devices, especially those with motors, run at a lower power factor, meaning real-world amp draw can run somewhat higher than the simple calculation suggests. Treat the result as a close estimate, not an exact reading.
What voltage do power station DC ports use?
Most power station car-style ports output 12V DC, matching a standard vehicle accessory outlet. Solar input voltage varies by model — check your specific unit's spec sheet rather than assuming a standard voltage.