Ohm's Law Calculator
Solve for any unknown in Ohm's Law — voltage, current, or resistance — by entering the other two. Also calculates power dissipation so you can pick the right resistor wattage rating.
Ohm's Law Fundamentals
Ohm's Law (V = I × R) is the foundation of electronics. Use this tool to find any one of the three parameters when you know the other two. Also shows power dissipation (P = V × I) which tells you if a resistor will overheat.
Enter two values to see the circuit
20 mA = 0.020 A
Fill in the two known values.
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