Ohm's Law Calculator (V, I, R, P)
Ohm's law and the power formula link the four basic electrical quantities.
Free tool
Result
Enter values to calculate.
Formula
- V = I × R
- P = V × I = I²R = V²/R
Example calculation
240 V across a 24 Ω heating element → 10 A and 2,400 W.
Practical HVAC use
Check heating elements, contactor coils, transformers and expected current.
Common mistakes
- Measuring resistance on an energized circuit.
- Applying Ohm's law directly to motors — their running current depends on impedance and load.
Related lessons
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Educational tool. Results are estimates from the stated formulas; always confirm with manufacturer data and the code adopted in your jurisdiction. All calculators