Amps to Watts Converter
Formula
Watts = Amps × Volts
Multiply amps by voltage to get watts (power). A 15A circuit at 120V can handle 1,800 watts.
How to use
- Enter the current in the Amps field.
- Enter the circuit's Voltage.
- Read the resulting power in watts.
Example
A 15-amp circuit at 120 volts handles 1,800 watts (15 × 120), the maximum power that circuit can supply.
Frequently Asked Questions
How many watts can a 15 amp circuit handle?
15A × 120V = 1,800W maximum (use 80% rule: 1,440W for continuous loads).
Is this formula for AC or DC power?
The simple Watts = Amps × Volts formula is exact for direct current (DC) and for resistive AC loads like heaters and incandescent bulbs. For motors, transformers, and other reactive AC devices, the real power in watts is lower because of the power factor, so the true formula becomes Watts = Amps × Volts × power factor. For quick household estimates the basic version is close enough, but electrical design work should account for power factor.
How many watts can a 20 amp circuit handle?
A 20-amp circuit at 120V can carry up to 2,400 watts at its maximum, but the safe continuous limit under the 80% rule is 1,920 watts. This is why 20-amp circuits are common in kitchens and workshops where appliances like microwaves, toasters, and power tools draw heavy loads. Always add up the wattage of everything on the circuit to avoid tripping the breaker.