Power Calculators

Power math is the language of electrical sizing. Watts describe real work. Amps describe current flow. Volts describe electrical pressure. Ohm's law and the power formula (P = V × I) connect them. Master these relationships and you can trace a problem from a tripped breaker back to an overloaded circuit or an undersized cable.

In AC systems, distinguish real power (watts) from apparent power (VA). Resistive loads like heaters and incandescent bulbs align closely. Motors, transformers, and switching power supplies draw extra apparent power. Your utility meter bills real power (with power factor penalties on some commercial tariffs), but your inverter or generator limit may be published in VA.

DC power calculations look simpler but still demand respect for losses. Every inverter conversion, every long cable run, and every connector adds resistance. A 1,200 W load at 12 V is 100 A on paper—real systems need heavier gauge wire, tight terminations, and fusing sized for that sustained current.

Three-phase and split-phase residential service introduce additional factors for larger workshops, well pumps, and commercial gear. Single-phase shortcut formulas do not always transfer. When in doubt, measure with a clamp meter under real operation instead of relying on nameplate guesses alone.

WattQuick power calculators help you convert between watts and amps at a given voltage, estimate circuit demand, and cross-check vendor claims. Use them while building load tables, before specifying breakers, and when validating whether a portable generator can start your largest motor load.