Watts, Amps & Volts Calculator
Calculate watts, amps or volts from the other two values, for basic DC electrical planning around your battery, solar or 12V system.
Result — watts
120.00
12V × 10A = 120.0W
Based on the basic power equation P = V × I (watts = volts × amps). This is a simplified DC calculation intended for planning purposes — it does not account for AC power factor, wiring losses, or other real-world electrical effects.
Formula
Watts = Volts × Amps. Rearranged: Amps = Watts ÷ Volts, and Volts = Watts ÷ Amps.
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Frequently Asked Questions
How many amps does a 300W appliance draw at 12V?+
300W ÷ 12V = 25A. Use the calculator above with your own figures for other combinations.
Does this work for AC circuits too?+
This simplified formula (P = V × I) works well for DC circuits like 12V/24V battery systems. AC circuits with reactive loads involve power factor, which this basic calculator doesn't model — for AC appliance sizing, see the Inverter Size Calculator instead.
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