What are the power formulas?

P = V × I (voltage times current), P = I² × R (current squared times resistance), and P = V² / R (voltage squared divided by resistance). All three give power in watts.

Which formula should I use?

Use whichever two quantities you already know. The calculator offers all three combinations so you never have to convert first.

Is anything uploaded?

No — every calculation runs locally in your browser, with no network requests.

Power (Watts) Calculator

Electrical power from voltage, current and resistance.

Electrical power (watts) calculator

Electrical power in watts can be found three equivalent ways, derived from Ohm’s law:

P = V × I — voltage times current
P = I² × R — current squared times resistance
P = V² / R — voltage squared divided by resistance

Pick the pair of values you know, type them in, and the power updates instantly — all in your browser.