Free Ohm's Law calculator. Enter any two values of voltage, current, or resistance to calculate the third. Also shows power.
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Ohm's Law Calculator
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Formula
Formula
V = I × R | I = V ÷ R | R = V ÷ I | P = V × I
V = Voltage (Volts) · I = Current (Amps) · R = Resistance (Ohms) · P = Power (Watts). Enter any two to calculate all others.
Frequently Asked Questions
What is Ohm's Law?+
Ohm's Law states that Voltage = Current × Resistance (V=IR). It describes the relationship between voltage, current, and resistance in electrical circuits.
How do I calculate resistance?+
R = V ÷ I. Enter voltage and current, leave resistance blank. Example: 12V ÷ 2A = 6 Ohms.
What is power in Ohm's Law?+
Power (Watts) = Voltage × Current (P = V×I). Also P = I²R = V²/R.