4,500 Watts to Amps — How Many Amps Is 4,500 Watts?
4,500 Watts equals 37.50 amps at 120V or 18.75 amps at 240V. Common 4500W devices: Standard water heater element.
4,500 Watts Amps at Every Voltage
| Voltage | Single Phase | Three Phase |
|---|---|---|
| 120V | 37.50A | 21.65A |
| 208V | 21.63A | 12.49A |
| 240V | 18.75A | 10.83A |
| 277V | 16.25A | 9.38A |
| 480V | 9.38A | 5.41A |
The Formula
Single Phase: Amps = Watts ÷ Volts. For 4,500 Watts at 120V: 4500 ÷ 120 = 37.50A.
Three Phase: Amps = Watts ÷ (Volts × 1.732). For 4,500 Watts at 240V 3-phase: 4500 ÷ (240 × 1.732) = 10.83A.
With power factor: Amps = Watts ÷ (Volts × PF). A PF of 0.8 increases the current draw by 25%.
Wire and Breaker for 4,500 Watts at 120V
At 120V, 4,500 Watts draws 37.5A. Recommended: 8 AWG copper wire with a 40A breaker per NEC 310.16. For continuous loads (3+ hours), apply 125% rule. Use our Wire Size Calculator for exact sizing.
Common 4500W Devices
Standard water heater element. 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.