Electronics
Ohm’s Law Calculator
Solve Ohm’s law instantly: provide any two values (voltage, current, resistance) and the third is calculated automatically.
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Ohm’s Law
Solve for voltage, current, or resistance instantly.
Voltage
12 V · 12000 mV · 0.012 kV
Current
3 A · 3000 mA
Resistance
4 Ω · 0.004 kΩ · 0.000004 MΩ
Power
36 W
Ohm’s law
V = I × R
Rearranged forms compute current (I = V ÷ R) or resistance (R = V ÷ I). Power is also shown using P = V × I.
How to use
- Select which value to solve for.
- Enter the known quantities using volts, amps, and ohms.
- Read the solved value plus instantaneous power and unit-scaled outputs.
Example
Input: Solve for current: Voltage = 12 V, Resistance = 4 Ω
Output: Current = 3 A, Power = 36 W
FAQ & notes
Can I use milliamps or kilohms?
Yes—pick alternate units from the select inputs and the calculator handles conversions internally.
Does it support AC impedance?
This tool focuses on DC circuits. Use the Power Factor calculator for AC efficiency considerations.