How it works
Solve DC circuit values using Ohm's law (voltage, current, resistance, power).
Enter any two of voltage (V), current (A), and resistance (Ω). The calculator derives the missing value and the electrical power.
Formula
V = I × R; I = V ÷ R; R = V ÷ I; P = V × I.
V- Voltage (V)
I- Current (A)
R- Resistance (Ω)
P- Power (W)
Examples
- 12 V across 4 ΩVoltage 12 V · resistance 4 ΩCurrent 3 A · power 36 W
Frequently asked questions
Does this apply to AC circuits?
This uses the DC form of Ohm's law. For AC you would also need reactance and phase (a separate tool).
Why must I enter exactly two values?
Ohm's law relates three quantities, so any two fully determine the third and the power.
How to read the result
The results are consistent only when all four values agree with V = I × R; the calculator derives them from whatever two you provide.
Limitations
DC (resistive) circuits only; no reactance, impedance, or AC phase.
Source: Ohm's law (V = IR) and electrical power (P = VI).