How It Works

The calculator uses Ohm's Law to determine resistance from voltage and current. Divide the voltage across the circuit by the current flowing through it to find the resistance.

R = V ÷ I, where R is resistance in ohms (Ω), V is voltage in volts (V), and I is current in amperes (A).

Example

For example, if a circuit has 12 V and a current of 3 A, the resistance is 4 Ω because R = 12 ÷ 3 = 4 Ω.

Frequently Asked Questions

What is the formula for resistance?

Using Ohm's Law, resistance is calculated with R = V ÷ I, where V is voltage in volts and I is current in amperes.

How do you calculate resistance from voltage and current?

Divide the voltage by the current. For example, 12 V ÷ 3 A = 4 Ω.

What unit is electrical resistance measured in?

Electrical resistance is measured in ohms (Ω).

What is Ohm's Law?

Ohm's Law describes the relationship between voltage, current, and resistance in an electrical circuit. It can be written as V = IR.

What is the resistance if the voltage is 12 V and the current is 3 A?

The resistance is 4 Ω. Using R = V ÷ I, the calculation is 12 ÷ 3 = 4 Ω.

Can resistance be calculated if voltage and current are known?

Yes. When voltage and current are known, divide the voltage by the current to calculate resistance using Ohm's Law.