Ohm's Law Calculator
Calculate voltage, current, or resistance using Ohm's Law. Also computes electrical power.
A
Ω
Examples
V = I × R = 2 × 100 = 200V
Voltage
200 V
Current
2 A
Resistance
100 Ω
Power
400 W
High power — typical for heaters, motors, or power tools.
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Examples
How It Works
Formula
Variables
- Voltage(V)
- Current(A)
- Resistance(Ω)
- Electrical power(W)
Select what to solve for: voltage (V=I×R), current (I=V/R), or resistance (R=V/I). Enter the two known values and the calculator finds the unknown plus the power (P=V×I).
Ohm's Law links voltage, current, and resistance with V = I × R. The calculator picks the rearranged form that matches your two knowns: voltage as a product, or current and resistance as ratios. It then multiplies voltage by current to report dissipated power. Stick to volts, amperes, and ohms so power comes out in watts directly.
Frequently Asked Questions
01What is Ohm's Law?
Ohm's Law states that voltage (V) equals current (I) multiplied by resistance (R): V = I × R. It is the fundamental relationship in electrical circuits.
02What units are used?
Voltage is measured in Volts (V), current in Amperes (A), and resistance in Ohms (Ω). Power is in Watts (W).
03How is electrical power calculated?
Power (P) = Voltage × Current = V × I. It can also be expressed as P = I²R or P = V²/R.
04What does resistance mean?
Resistance is the opposition to current flow in a circuit, measured in Ohms (Ω). Higher resistance means less current for a given voltage.
05When does Ohm's Law not apply?
Ohm's Law applies to linear (ohmic) components. Non-linear components like diodes and transistors have variable resistance and require different models.