300 Watts to Amps — How Many Amps Is 300 Watts?
300 Watts equals 2.50 amps at 120V or 1.25 amps at 240V. Common 300W devices: Blender, laptop + monitor.
300 Watts Amps at Every Voltage
| Voltage | Single Phase | Three Phase |
|---|---|---|
| 120V | 2.50A | 1.44A |
| 208V | 1.44A | 0.83A |
| 240V | 1.25A | 0.72A |
| 277V | 1.08A | 0.63A |
| 480V | 0.63A | 0.36A |
The Formula
Single Phase: Amps = Watts ÷ Volts. For 300 Watts at 120V: 300 ÷ 120 = 2.50A.
Three Phase: Amps = Watts ÷ (Volts × 1.732). For 300 Watts at 240V 3-phase: 300 ÷ (240 × 1.732) = 0.72A.
With power factor: Amps = Watts ÷ (Volts × PF). A PF of 0.8 increases the current draw by 25%.
Wire and Breaker for 300 Watts at 120V
At 120V, 300 Watts draws 2.5A. 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 300W Devices
Blender, laptop + monitor. 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.