Power Conversion Calculator
Watts, Volts & Amps Conversion Formulas
Generator Sizing Calculations
Generator sizing requires converting between watts and amps: a 5000W generator at 240V provides 20.83A. Starting watts (surge) can be 2–3× running watts for motor loads. A home with 30A service at 240V has 7,200W maximum capacity. Essential loads: refrigerator (700W running, 2,100W starting), sump pump (800W running, 2,400W starting), furnace blower (500W).
Circuit Breaker Load Planning
NEC (National Electrical Code) limits continuous loads to 80% of breaker rating. A 20A circuit at 120V supports 2,400W maximum, but only 1,920W continuous (80%). A 15A circuit: 1,800W max, 1,440W continuous. Converting watts to amps ensures circuits aren't overloaded: Amps = Watts ÷ Volts. See our watt to voltage converter for individual calculations.
Home Backup Power System Design
Designing a home backup system requires totaling all loads in watts: lighting (500W), refrigerator (700W), internet/router (50W), phone charging (25W), furnace (500W) = 1,775W minimum inverter capacity. At 12V battery bank, that draws 148A — requiring thick cables and proper fusing. At 48V, current drops to 37A. For battery capacity calculations, see our battery conversion tools.