Ohm's Law Calculator
Instantly solve Ohm’s Law equations with our free online calculator. Calculate voltage, current, resistance, or power with just two known values.
Ohm's Law Calculator
Enter any two known values to calculate the other two. The results will update automatically.
Understanding Ohm's Law
This section introduces the fundamental principles of Ohm's law. It provides a foundational understanding of the relationship between voltage, current, and resistance, which is essential before diving into the more complex formulas and applications discussed later.
Ohm's Law states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points. It is one of the most fundamental laws in electronics and electrical engineering.
The primary formula is:
V = I × R
- V is the Voltage, measured in Volts (V).
- I is the Current, measured in Amperes (A).
- R is the Resistance, measured in Ohms (Ω).
The Power Wheel of Formulas
This "Power Wheel" is a comprehensive reference that expands on the basic V=IR formula to include Power (P). It organizes all 12 derived formulas, allowing you to easily find the correct equation to solve for any unknown variable when you know two others. It is an invaluable tool for quick reference.
Voltage (V)
I × R
P / I
√(P × R)
Current (I)
V / R
P / V
√(P / R)
Resistance (R)
V / I
P / I²
V² / P
Power (P)
V × I
I² × R
V² / R
Interactive Visualization
This chart provides a dynamic way to see Ohm's law in action. By adjusting the resistance with the slider, you can observe how the linear relationship between voltage and current changes. This helps to build an intuitive understanding of how these electrical properties are interconnected.