Use this Ohm’s Law Calculator to calculate voltage, current, resistance, and power in a resistive circuit. Enter any two known values, and the calculator determines the remaining electrical parameters using Ohm’s Law.It is useful for quickly calculating resistor values, circuit current, voltage drops, and power dissipation when designing or troubleshooting basic electronic circuits.
Enter any two values. The remaining two are calculated automatically.
Results
- Voltage
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- Current
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- Resistance
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- Power
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How it works
Ohm's law describes the relationship between voltage, current and resistance in a resistive circuit. Combined with the power equation, knowing any two of the four quantities lets you calculate the other two.
Ohm's Law Formulas
V = I × R
P = V × I
P = I² × R
P = V² / R
Notes
- V is voltage in volts (V), I is current in amps (A), R is resistance in ohms (Ω) and P is power in watts (W).
- Ohm's law applies to resistive (linear) components. LEDs, diodes and transistors are non-linear and need their own calculations.
- Choose a resistor power rating at least twice the calculated power.
