Ohm's law: current, voltage, resistance calculator
Ohm's law links voltage, current, and resistance, and the power formula adds a fourth quantity. Fill in any two fields — the calculator computes the remaining two.
Input data
Fill in any two fields — the rest are calculated automatically.
Result
Bright highlights what you entered; blue is what the formulas calculated.
Voltage, U
—
В
Current, I
—
А
Resistance, R
—
Ом
Power, P
—
Вт
How it's calculated
- Ohm's law links three quantities: U = I · R. Knowing any two, you get the third by rearranging the formula.
- Power adds a fourth: P = U · I, and via Ohm's law also P = I² · R and P = U² / R.
- So any two of the four values are enough: the calculator plugs them into the right formula and outputs the remaining two.
Example: U = 12 V and R = 4 Ω → current I = 12 / 4 = 3 A, power P = 12 · 3 = 36 W.
Formulas: U = I·R and P = U·I (Ohm's law and the DC power definition).
This is an estimate
Verify final values against current standards, the project design, and equipment nameplates.