Ohm's Law & Electrical Power Calculator
Use our free online Ohm's Law Calculator to perform fast, accurate calculations with instant formulas, step-by-step arithmetic, and verified reference benchmarks.
Ohm's Law Calculator
Instant Live Computation • Zero Waiting
Adjust inputs on the left for instantaneous live computation.
How to Calculate: The Ohm's Law Calculator Formula
Fundamental relationship in electrical physics relating potential difference (V in Volts), electric current (I in Amperes), resistance (R in Ohms), and power (P in Watts).
Step-by-Step Calculation Guide
- Input any two known electrical parameters (Voltage, Current, Resistance, or Power).
- Apply Ohm's Law and Joule's Law algebraic equations.
- Review remaining two solved electrical properties.
- Inspect circuit safety and power dissipation.
Practical Ohm's Law Calculator Examples
12 Volts across a 4 Ohm resistance.
1,200 Watt heater on a 120V circuit.
Ohm's Law Wheel of 12 Electrical Formulas
Official reference values and benchmark classifications based on standard institutional guidelines.
| Solve For | Using Voltage & Current | Using Current & Resistance | Using Voltage & Resistance | Using Power |
|---|---|---|---|---|
| Voltage (V) | V = P / I | V = I × R | V = √(P × R) | V = P / I |
| Current (I) | I = V / R | I = P / V | I = √(P / R) | I = P / V |
| Resistance (R) | R = V / I | R = V² / P | R = P / I² | R = V² / P |
| Power (P) | P = V × I | P = I² × R | P = V² / R | P = V × I |
Frequently Asked Questions about Ohm's Law Calculator
What is 1 Volt, 1 Amp, and 1 Ohm?
1 Volt is the electrical potential needed to push 1 Ampere of current through 1 Ohm of electrical resistance.
How does increasing resistance affect current?
At constant voltage, increasing resistance inversely decreases current flow (I = V / R).
What is the difference between AC and DC circuits?
Direct Current (DC) flows continuously in one direction. Alternating Current (AC) reverses direction periodically (50Hz or 60Hz), where impedance (Z) replaces simple resistance.
Why do wires heat up when carrying high current?
Joule heating (P = I²R) converts electrical energy into thermal heat proportional to the square of the current, which is why high-current circuits require thicker gauge wire.