Solve Ohm's Law for any unknown — voltage, current, or resistance — by entering any two known values. The tool also calculates power (P = V×I).
How it works
- Provide any two of the three variables: Voltage, Current, or Resistance.
- Leave the third variable blank to identify it as the target for calculation.
- The engine uses Ohm's Law (V=IR) to instantly calculate the missing value and total power.
Frequently asked questions
What are typical household voltages?
120 V AC in North America, 230 V AC in Europe. DC circuits vary widely — 5 V USB, 12 V automotive, 48 V PoE.
What unit is resistance measured in?
Ohms (Ω). Real components range from milliohms (0.001 Ω) in wire to megaohms (1,000,000 Ω) in insulation.
How do I measure resistance safely?
Always power off the circuit before measuring resistance with a multimeter. Never measure resistance in a live circuit.