⚡ Ohm's Law Calculator
Enter any two known electrical values — Voltage, Current, Resistance, or Power — and calculate the other two instantly.
Known Values
Your Result
Units: Voltage in volts (V), Current in amps (A), Resistance in ohms (Ω), Power in watts (W).
How the Ohm's Law Calculator Works
Ohm's Law describes the relationship between voltage, current, and resistance in an electrical circuit. Combined with the power formula, any two known values are enough to solve for all four quantities.
Formulas
I = V / R = P / V = √(P / R)
R = V / I = V² / P = P / I²
P = V × I = I² × R = V² / R
Frequently Asked Questions
What is Ohm's Law?
Ohm's Law states that the current through a conductor is directly proportional to the voltage and inversely proportional to the resistance: V = I × R.
How is power related to Ohm's Law?
Electrical power equals voltage times current (P = V × I). Combining this with Ohm's Law lets you derive power from any two of V, I, or R.
Can I calculate all four values from just two?
Yes. Any two of Voltage, Current, Resistance, and Power uniquely determine the other two using the Ohm's Law and power formulas above.