Ohm’s Law Calculator
Solve voltage, current, or resistance in a simple circuit.
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How Ohm’s law works
This Ohm’s law calculator solves voltage, current, or resistance in a simple circuit. It is useful for basic electronics, circuit practice, LED resistor estimates, lessons, and quick checks.
Make sure the circuit can reasonably be modeled with Ohm’s law. Components such as diodes, motors, batteries with internal resistance, and nonlinear loads may need more detailed analysis.
Formula or logic
- Voltage V = Current I × Resistance R
- Current I = Voltage V ÷ Resistance R
- Resistance R = Voltage V ÷ Current I
Example
If voltage is 12 V and resistance is 6 Ω, current is 2 A. For real components, also check power rating and safety margin.
Common questions
Does Ohm’s law apply to every circuit?
No. It works well for linear resistive circuits, but nonlinear components need more complete models.
How do A and mA convert?
1 A equals 1,000 mA.
Is calculating current enough for safety?
No. Real circuits also need power, heat, ratings, and protection checks.