Ohms Law Calculator

The Ohms Law Calculator helps you quickly calculate voltage, current, or resistance using Ohm’s Law. Simply enter any two known values, choose the value you want to find, and get your result instantly. This free tool is useful for students, electricians, electronics hobbyists, and anyone learning about electrical circuits.

Calculate voltage, current or resistance using two known electrical values.

Calculate quantity Choose the electrical value you want to find.

Voltage (V)

Current (I)

Resistance (R)

Enter exactly two known values. Leave the selected target and the unused field blank. Your answer updates automatically as you enter values.

Calculation Results

View your answer, the formula used and common Ohm’s law equations.

Current

2 A

Default example: 12 V ÷ 6 Ω = 2 A.

Formula Used

I = V / R

Current equals voltage divided by resistance.

Ohm’s Law Formulas

Calculate Voltage V = I × R

Calculate Current I = V / R

Calculate Resistance R = V / I

Ohm’s Law V = I × R I = V / R R = V / I

Units: V = volts, A = amperes (amps), and Ω = ohms. These equations describe the relationship between voltage, current and resistance for an ohmic circuit. Division by zero is not permitted.

How to Use the Ohms Law Calculator

Using this calculator is simple:

Enter the voltage, current, or resistance values you already know.
Select the value you want to calculate.
The calculator will automatically display the result.
Use Clear All to remove the values or Reload Defaults to restore the default settings.

For accurate results, enter any two known electrical values and leave the value you want to calculate for the tool to determine.

Ohm’s Law Formula

Ohm’s Law describes the relationship between voltage, current, and resistance in an electrical circuit.

The basic formula is:

V = I × R

Where:

V = Voltage, measured in volts (V)
I = Current, measured in amperes (A)
R = Resistance, measured in ohms (Ω)

You can rearrange the formula to calculate the other values:

Voltage: V = I × R
Current: I = V ÷ R
Resistance: R = V ÷ I

For example, if a circuit has a voltage of 12 V and a resistance of 6 Ω, the current is 2 A.

Why Use an Ohm’s Law Calculator?

Calculating electrical values manually can take time, especially when you are working with different circuit measurements. This calculator makes the process faster and helps you check your calculations without remembering every formula.

It is useful for electrical engineering students, electronics projects, basic circuit analysis, and everyday learning about voltage, current, and resistance.

Frequently Asked Questions

1. What is an Ohm’s Law Calculator?

An Ohm’s Law Calculator is a free online tool that calculates voltage, current, or resistance when you enter the other two known values.

2. What is the formula for Ohm’s Law?

The main formula is V = I × R, where V represents voltage, I represents current, and R represents resistance.

3. How do I calculate current using Ohm’s Law?

Divide voltage by resistance using the formula I = V ÷ R. For example, 12 volts divided by 6 ohms gives a current of 2 amperes.

4. How do I calculate resistance?

Divide voltage by current using the formula R = V ÷ I. For example, 12 volts divided by 2 amperes gives a resistance of 6 ohms.

5. Can I calculate voltage, current, and resistance with this tool?

Yes. You can calculate any one of these three values by entering the other two known values and selecting the quantity you want to find.

Note: This calculator uses the basic Ohm’s Law relationship for circuits where voltage and current are proportional. Always follow appropriate electrical safety precautions when working with real circuits.

Ohms Law Calculator