What is Ohm’s Law?

Ohm’s Law is one of the most important principles in physics and electrical engineering. It defines the relationship between voltage, current, and resistance in an electrical circuit.
The formula for Ohm’s Law is
V = I × R
Where:
V = Voltage (in volts)
I = Current (in amperes)
R = Resistance (in ohms)
This simple equation forms the foundation of all electrical calculations. By knowing any two values, you can easily find the third using our Ohm’s Law Calculator.

How to Use the Ohm’s Law Calculator

The Ohm’s Law Resistance Calculator on All Calculator is user-friendly and works in just a few steps:

Step 1: Choose the two values you already know

You can select which value you’d like to find — Voltage (V), Current (I), or Resistance (R).

Step 2: Enter your known values

Enter Voltage in volts (V)
Enter Current in amperes (A)
Enter Resistance in ohms (Ω)

Step 3: Click “Calculate”

Once you click the button, the Ohm Calculator instantly applies the formula for Ohm’s Law to give you accurate results.

Formulas Used by the Ohm’s Law Calculator

Our Ohm’s Law online calculator uses standard electrical equations to calculate your results precisely:
Voltage (V)
V = I × R
Example: If I = 0.5 A and R = 4 Ω, then V = 0.5 × 4 = 2 V
Current (I)
I = V ÷ R
Example: If V = 2 V and R = 4 Ω, then I = 2 ÷ 4 = 0.5 A
Resistance (R)
R = V ÷ I
Example: If V = 2 V and I = 0.5 A, then R = 2 ÷ 0.5 = 4 Ω
Power (P)
P = V × I
Example: If V = 2 V and I = 0.5 A, then P = 2 × 0.5 = 1 W

Example Exercises

Example 1: Voltage = ?
Current = 0.2 A
Resistance = 15 Ω
→ V = 0.2 × 15 = 3 V
Example 2:
Current = ?
Voltage = 12 V
Resistance = 6 Ω
→ I = 12 ÷ 6 = 2 A
Example 3:
Resistance = ?
Voltage = 10 V
Current = 5 A
→ R = 10 ÷ 5 = 2 Ω
Example 4 (Power):
Power = ?
Voltage = 9 V
Current = 0.3 A
→ P = 9 × 0.3 = 2.7 W

Why Use All Calculator’s Ohm’s Law Calculator?

Accurate and Fast Results: Get instant and precise values based on Ohm’s Law power formula — no need to calculate manually.
Easy to Use for Everyone: Students, teachers, electricians, or engineers — anyone can use this simple tool without prior technical knowledge.
Free and Online: Works directly from your browser — no downloads, sign-ups, or installations.
Perfect for Learning and Projects: Ideal for physics assignments, lab work, and electrical circuit testing.

Pro Tips

Always use consistent units (Volts, Amperes, Ohms).
Double-check that your inputs are in the correct fields.
Experiment with different values to see how they affect results.

FAQs

What is the formula for Ohm’s Law?

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

Can I use this calculator on mobile devices?

Yes! The Ohm’s Law Calculator by All Calculator works perfectly on desktops, tablets, and smartphones.

What is the Ohm’s Law power formula?

The power formula derived from Ohm’s Law is P = V × I, where P is power in watts.

Can this calculator find resistance or current?

Yes. This Ohm’s Law resistance calculator can compute any one value when the other two are provided.