100 Watts to Amps, How Many Amps Is 100 Watts?
100 Watts equals 0.83 amps at 120V or 0.42 amps at 240V. Common 100W devices: LED bulb, USB charger, small fan.
100 Watts Amps at Every Voltage
| Voltage | Single Phase | Three Phase |
|---|---|---|
| 120V | 0.83A | 0.48A |
| 208V | 0.48A | 0.28A |
| 240V | 0.42A | 0.24A |
| 277V | 0.36A | 0.21A |
| 480V | 0.21A | 0.12A |
The Formula
Single Phase: Amps = Watts ÷ Volts. For 100 Watts at 120V: 100 ÷ 120 = 0.83A.
Three Phase: Amps = Watts ÷ (Volts × 1.732). For 100 Watts at 240V 3-phase: 100 ÷ (240 × 1.732) = 0.24A.
With power factor: Amps = Watts ÷ (Volts × PF). A PF of 0.8 increases the current draw by 25%.
Wire and Breaker for 100 Watts at 120V
At 120V, 100 Watts draws 0.8A. Recommended: 14 AWG copper wire with a 15A breaker per NEC 310.16. For continuous loads (3+ hours), apply 125% rule. Use our Wire Size Calculator for exact sizing.
Common 100W Devices
LED bulb, USB charger, small fan. Always check the device nameplate for exact wattage, rated watts may differ from actual consumption.
Disclaimer: Calculations are for reference. Verify with device nameplate. Consult a licensed electrician for installations.