Ohms Law Calculator
Enter any two values to calculate the remaining two values
Ohms Law Calculator
The Ohm’s Law Calculator is a simple yet powerful tool designed to calculate voltage (V), current (I), resistance (R), and power (P) in any electrical circuit.
By entering any two known values, the calculator instantly applies Ohm’s Law and Joule’s Law to find the remaining quantities.
It’s a must-have for electrical engineers, technicians, students, and DIY enthusiasts working on electronics or circuit design.
What Is Ohm’s Law?
Ohm’s Law is one of the most fundamental principles in electrical and electronic engineering.
It defines the relationship between voltage, current, and resistance in an electrical circuit.
In simple words:
“The current flowing through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance.”
Formula:
V = I × R
Where:
V = Voltage (in Volts)
I = Current (in Amperes or Amps)
R = Resistance (in Ohms, symbol Ω)
Ohm’s Law applies to resistive circuits (those without inductors or capacitors) and works for both DC and AC power sources.
Ohm’s Law and Power Formula Summary
| Symbol | Quantity | Unit | Formula Example |
|---|---|---|---|
| V | Voltage | Volts (V) | V = I × R |
| I | Current | Amperes (A) | I = V ÷ R |
| R | Resistance | Ohms (Ω) | R = V ÷ I |
| P | Power | Watts (W) | P = V × I |
Electrical Power (Joule’s Law)
Electrical Power measures how quickly electrical energy is consumed or transferred in a circuit.
It’s expressed in Watts (W) and can be calculated using these formulas:
P = V × I
P = V² ÷ R
P = I² × R
Where:
P = Power (Watts)
V = Voltage (Volts)
I = Current (Amperes)
R = Resistance (Ohms)
These power equations are used to determine how much energy a component uses or how much heat a resistor will produce.
Ohm’s Law Formula Wheel
The Ohm’s Law Formula Wheel is a simple visual guide that shows how Voltage (V), Current (I), Resistance (R), and Power (P) are mathematically related.
Choose the value you need to calculate in the center, then find the formula that connects your two known values.
This wheel helps students and engineers remember all possible equations at a glance.
How to Use the Ohm’s Law Calculator:
Using this calculator is quick and easy.
Here’s how you can do it in just a few steps:
Choose what you want to calculate — Voltage (V), Current (I), Resistance (R), or Power (P).
Enter any two known values in the input boxes.
Click on the “Calculate” button.
The calculator will automatically compute the missing value using the correct Ohm’s Law or Power formula.
You can also reset the fields anytime to start a new calculation.
Example:
If you know Voltage = 12V and Current = 2A, the calculator will show Resistance = 6Ω and Power = 24W instantly.
Related Calculators:
Ohm’s Law is used to calculate the relationship between voltage, current, and resistance in an electrical circuit. It helps design and troubleshoot circuits easily.
To find voltage, multiply current (I) by resistance (R) using the formula V = I × R.
Yes, this calculator also calculates electrical power (P) using formulas like P = V × I, P = V² ÷ R, or P = I² × R.
Yes, Ohm’s Law applies to both AC and DC circuits as long as the circuit is purely resistive (no capacitors or inductors).
Voltage is measured in volts (V), current in amperes (A), resistance in ohms (Ω), and power in watts (W).