Free to use, no account
Ohm’s Law Calculator
Solve any two missing values in an ideal DC resistive circuit, or calculate the equivalent resistance of a series or parallel resistor network.
How do I use the Ohm’s law calculator?
Enter exactly two positive values among voltage (V), current (A), resistance (Ω) and power (W). For example, 12 V and 6 Ω give 2 A and 24 W. Or choose the network mode and enter 2 to 20 resistors.
Frequently asked questions
How do I use the Ohm’s law calculator?
Enter exactly two positive values among voltage (V), current (A), resistance (Ω) and power (W). For example, 12 V and 6 Ω give 2 A and 24 W. Or choose the network mode and enter 2 to 20 resistors.
Are my circuit values uploaded?
No. Calculations run in this browser; your values are not uploaded or saved.
What does Ohm’s law calculate?
For an ideal resistive DC circuit, it relates voltage, current and resistance: V=IR. Power follows P=VI, so any two known positive values determine the other two.
How is equivalent resistance calculated?
Resistors in series add. For parallel resistors, add their reciprocals and take the reciprocal of that sum. This calculator supports 2 to 20 positive resistor values.
Can I use this to design a safe electrical circuit?
No. It is basic idealized arithmetic, not a safety assessment. AC, heat, component power ratings, wiring and local code requirements need separate qualified review.