Ohm’s Law Calculator

Ohm’s Law is essential for electrical circuit analysis, whether you’re an engineer, student, or hobbyist. To simplify complex calculations, we’ve created a free, easy-to-use online Ohm’s Law calculator that helps you master the concepts quickly.

Ohm’s Law describes the relationship between voltage, current, and resistance in an electrical circuit. It’s a fundamental concept that allows you to design and analyze circuits and understand electricity flows.

Our free online calculator is here to make those calculations easy and precise.

What is Ohm’s Law

Let’s start by defining some key terms:

• Voltage (V): The electrical pressure that drives current through a circuit. Think of it as the force pushing electrons. It is measured in Volts (V).
• Current (I): The flow of electrical charge, or electrons, through a circuit. It is measured in Amperes (A or Amps).
• Resistance (R): It opposes the current flow in a circuit. It limits the current flowing through the circuit. It is measured in Ohms (Ω).

Now, here’s the formula for Ohm’s Law:

V = I * R

Where:

• V = Voltage (in volts)
• I = Current (in amps)
• R = Resistance (in ohms)

If you know the other two, this simple formula lets you calculate any of these values. To make it even easier, you can use the Ohm’s Law Triangle:

Here’s how you can rearrange the formula to solve for different variables:

• To Calculate Voltage (V): If you know the current (I) and resistance (R), multiply the two: V = I * R
• To Calculate Current (I): If you know the voltage (V) and resistance (R), divide the voltage by resistance: I = V / R
• To Calculate Resistance (R): If you know the voltage (V) and current (I), divide the voltage by current: R = V / I

Ohm’s Law Equation

Ohm’s law states the relationship between electric current and potential difference. The current flowing through most conductors is directly proportional to the voltage. Georg Simon Ohm, a German physicist, proved Ohm’s law experimentally.

V = IR,

where V is the voltage across the conductor, I is the current flowing through the conductor and R is the resistance the conductor provides to the current flow.

Quadrant 1: Power (watts)

Power is the rate at which energy is used or produced.

• V x I (Voltage times Current)
• I² x R (Current squared times Resistance)
• V² / R (Voltage squared divided by Resistance)

Quadrant 2: Voltage (volts)

Voltage is the electrical “pressure” that pushes current through a circuit.

• P / I (Power divided by Current)
• √(P x R) (Square root of Power times Resistance)
• R x I (Resistance times Current)

Quadrant 3: Current (amps)

Current is the flow of electrical charge through a circuit.

• P / V (Power divided by Voltage)
• √(P / R) (Square root of Power divided by Resistance)
• V / R (Voltage divided by Resistance)

Quadrant 4: Resistance (ohms)

Resistance is the opposition to current flow in a circuit.

• V² / P (Voltage squared divided by Power)
• V / I (Voltage divided by Current)
• P / I² (Power divided by Current squared)

How to Use the Ohm’s Law Calculator

1. Select the Variable to Solve For
   • Choose whether you want to calculate Voltage (V), Current (I), or Resistance (R).
2. Enter the Known Values
   • Input the two known variables. For example:
     • Voltage and Resistance to find Current.
     • Current and Resistance to find Voltage.
3. Press “Calculate”
   • Click the “Calculate” button, and the calculator will instantly display the result.

Example Calculations:

1. Find Current (I):
   • Given: Voltage = 10V, Resistance = 5Ω
   • Formula: I = V ÷ R
   • Calculation: I = 10 ÷ 5 = 2A
2. Calculate Voltage (V):
   • Given: Current = 2A, Resistance = 3Ω
   • Formula: V = I × R
   • Calculation: V = 2 × 3 = 6V