Ohm's Law Calculator

Solve for voltage

Voltage

12 V

The Numbers

  • Voltage: 12 V
  • Current: 2 A
  • Resistance: 6 Ω
  • Power: 24 W

Compare Calculations

Downloads

Includes your inputs and results for this calculation, plus any additional calculations you've compared.

How This Calculator Works

Ohm’s Law describes the fundamental relationship between voltage, current, and resistance in any electrical circuit: voltage equals current multiplied by resistance. Enter any two of the three, and this calculator finds the third, along with the power the circuit is using.

This is the general-purpose electrical relationship, distinct from the

Voltage Drop Calculator, which answers a more specific question — how much voltage is lost over a run of wire, given its gauge, length, and material.

The Formula

  • Voltage: V=I×RV = I \times R
  • Current: I=V÷RI = V \div R
  • Resistance: R=V÷IR = V \div I
  • Power (always computed): P=V×IP = V \times I

Like the Circle Calculator, none of these three variables has a single fixed “input” role — whichever two you know solve for the third — so they’re left uncolored rather than assigning one a fixed color it wouldn’t consistently play across every direction.

Worked Example

A circuit with 2 amps of current flowing through a 6 ohm resistor:

  1. Voltage: 2×6=122 \times 6 = 12 V.
  2. Power: 12×2=2412 \times 2 = 24 W.

All three solve-for modes agree: entering 12V and 6Ω finds 2A; entering 12V and 2A finds 6Ω — each direction gives the same consistent circuit.

Source: Ohm's Law, the fundamental voltage-current-resistance relationship.

Frequently Asked Questions

What is Ohm's Law?

Ohm's Law states that voltage equals current multiplied by resistance (V = I × R) in an electrical circuit — one of the most fundamental relationships in electronics, describing how these three quantities always relate to each other.

How is power related to voltage, current, and resistance?

Power (in watts) equals voltage multiplied by current: P = V × I. Combined with Ohm's Law, power can also be expressed as I²R or V²/R — this calculator always shows the P = V × I form once all three of voltage, current, and resistance are known.

How is this different from the Voltage Drop Calculator?

Ohm's Law is the general relationship between voltage, current, and resistance in any circuit. Voltage Drop Calculator answers a more specific, practical question — how much voltage is lost over a real run of wire, given its gauge, length, and material — which involves additional factors Ohm's Law alone doesn't capture.