Understanding the relationship between watts (power), amps (current), and volts (voltage) is fundamental to electrical work — whether you're sizing a circuit breaker, choosing an extension cord, installing a car amplifier, or troubleshooting a tripped breaker. This converter simplifies the process, handling both DC and AC calculations so you get the right answer every time.
| Watts (W) | Amps at 120V | Amps at 240V | Common Device |
|---|---|---|---|
| 60W | 0.50A | 0.25A | Light bulb |
| 100W | 0.83A | 0.42A | Incandescent bulb, laptop charger |
| 300W | 2.50A | 1.25A | Desktop computer, small TV |
| 500W | 4.17A | 2.08A | Mini fridge, microwave (low) |
| 750W | 6.25A | 3.13A | Space heater (low), microwave |
| 1000W | 8.33A | 4.17A | Microwave, coffee maker |
| 1500W | 12.50A | 6.25A | Space heater, hair dryer |
| 2000W | 16.67A | 8.33A | Portable heater, vacuum |
| 3000W | 25.00A | 12.50A | Window AC, EV charger (L1) |
| 5000W | 41.67A | 20.83A | Large AC, EV charger (L2) |
US homes typically have 15A or 20A circuits. A 15A circuit at 120V can handle 1,800W (but should be limited to 1,440W for continuous loads — the 80% rule). Before adding a 1500W space heater to a circuit already running a 500W computer and 200W of lighting (total 2,200W = 18.3A), you'd exceed the 15A breaker capacity. Our converter helps you avoid these dangerous overloads.
Extension cords are rated by amperage. A 13A cord can handle up to 1,560W at 120V. Running a 1800W pressure washer through it would overload the cord, creating a fire hazard. Check the wattage of your device and convert to amps to ensure your extension cord is properly rated.
A 400W solar panel producing power at 24V generates 16.67A. Your charge controller and wiring must handle this current. When planning solar installations, converting watts to amps at your system voltage helps you select appropriate wire gauges and breakers.
Car audio amplifiers are rated in watts at the car's 12V (or 14.4V running) electrical system. A 1000W amplifier at 12V draws 83.3A — which is why car audio installations require heavy-gauge power wire and often upgraded alternators.
Not all electrical loads are equal. A pure resistance load (heater, incandescent bulb) has a power factor of 1.0, so watts = volts × amps exactly. Motors, computers, and LED lights have lower power factors (0.6–0.95), meaning they draw more amps than the simple watts ÷ volts calculation suggests. Our AC calculator accounts for this.
For 120V circuits: divide watts by 120 to get amps. For a quick estimate, divide by 100 and add 20%. Example: 1500W ÷ 120 = 12.5A. Quick method: 1500 ÷ 100 = 15, then 15 × 0.8 = 12A (close enough for a safety check). For 240V: divide by 240, or divide by 200 and subtract a bit.
Watts measure power (the rate of energy use), while amps measure current (the flow of electrons). The relationship depends on voltage (electrical pressure). The same 100W device draws 0.83A at 120V but only 0.42A at 240V. Without voltage, the conversion is impossible.
The circuit breaker will trip to protect the wiring from overheating and potentially causing a fire. If a breaker repeatedly trips, you're overloading the circuit. Never replace a breaker with a larger one without ensuring the wiring can handle the increased current.
As a general guide: 14 AWG for up to 15A, 12 AWG for up to 20A, 10 AWG for up to 30A, 8 AWG for up to 40A, 6 AWG for up to 55A. Always consult the NEC (National Electrical Code) or a licensed electrician for specific installations.
Kilowatt-hours measure energy consumption over time (power × time). A 1000W (1 kW) device running for 1 hour uses 1 kWh. Your electricity bill is based on kWh. To convert watts to kWh, multiply watts by hours used, then divide by 1,000.
Use our free online Watts to Amps converter for instant, accurate calculations every time.