Ohm's Law & Power Calculator
Free · works offline · no account · NEC 2023 tables
Enter any two values — volts, amps, ohms, or watts — and OhmBase solves the other two. The wheel, without the wheel.
Open the free calculator →How the math works
V = I × R ties voltage, current, and resistance together; P = V × I ties in power. Every other arrangement (I = P/V, R = V²/P…) is algebra on those two.
Worked example
120 V circuit drawing 10 A
- R = V ÷ I = 120 ÷ 10 = 12 Ω
- P = V × I = 120 × 10 = 1,200 W
FAQ
- Does this work for AC circuits?
- For resistive loads, yes. Reactive loads (motors, ballasts) add power factor — true watts = V × A × PF — so treat the result as apparent power unless the load is resistive.
- What if I enter more than two values?
- OhmBase solves from the first consistent pair it finds — clear the fields you want computed.