Home & workshop Conversions
Watts to amps
Power
W
Voltage
V
Power factor
Resistive loads are 1; motors are 0.8–0.9Supply
Current 12.5 A
1500 W ÷ 120 V
In milliamps 12,500 mA
At 125% for continuous use 15.63 A
Equivalent resistance 9.6 Ω
A = W ÷ V
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320 × 100
Amps equal watts divided by volts. A 1,500 W appliance draws 12.5 A at 120 V but only 6.5 A at 230 V — the same power, half the current, which is the entire argument for higher distribution voltages.
How to convert watts to amps
1 Enter the appliance wattage from its label.
2 Enter the supply voltage where it will be used.
3 Read the current draw.
4 Use the 125% row if the appliance runs for three hours or more at a time.
There is no single watts-to-amps factor, which is why this needs a calculator rather than a chart. Current depends on voltage, and the same appliance rated in watts pulls wildly different currents on a 12 V battery, a 120 V outlet and a 230 V one. On AC the power factor matters too: an electric heater is purely resistive and converts cleanly, but a motor or a switch-mode supply draws more current than the wattage alone implies.
Questions
12.5 A at 120 V, 6.5 A at 230 V, or 125 A at 12 V. Voltage decides it.
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300 × 250
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