Ohm's Law Calculator
Compute voltage, current, resistance, and power using Ohm's Law
Calculator
Leave unknown values blank. You can also select the unit for each input and result.
About the Ohm’s Law Calculator
The Ohm’s Law Calculator helps you quickly compute the relationship between voltage (V), current (I), resistance (R), and power (P) in any electrical circuit. Simply enter any two known values, and the calculator automatically determines the remaining parameters. This tool is ideal for electrical engineers, technicians, and students working with DC or AC circuits.
What You Can Calculate
- Voltage (V): The electrical potential difference or “pressure” that drives current through a circuit.
- Current (I): The rate of flow of electric charge, measured in amperes (A).
- Resistance (R): The opposition to current flow, measured in ohms (Ω).
- Power (P): The rate at which electrical energy is converted into heat, light, or motion, measured in watts (W).
Formulas Used in the Calculator
The calculator applies the fundamental equations of Ohm’s Law and power relationships:
- V = I × R (Voltage = Current × Resistance)
- I = V ÷ R (Current = Voltage ÷ Resistance)
- R = V ÷ I (Resistance = Voltage ÷ Current)
- P = V × I (Power = Voltage × Current)
- P = I² × R (Power based on current and resistance)
- P = V² ÷ R (Power based on voltage and resistance)
These formulas form the foundation of electrical and electronic circuit design, allowing for accurate analysis of circuit parameters in both theoretical and practical applications.
How to Use the Calculator
- Enter any two known quantities — for example, voltage and resistance.
- Select the appropriate units for each value (volts, amps, ohms, or watts).
- The calculator will automatically compute the remaining parameters using Ohm’s Law.
- Adjust inputs as needed to explore different circuit conditions and power relationships.
Applications of Ohm’s Law
Ohm’s Law is one of the most important principles in electrical and electronic engineering. It helps designers and technicians analyze how voltage, current, and resistance interact in any circuit. Applications include:
- Designing and troubleshooting DC circuits and AC networks
- Calculating required resistor values for LEDs, sensors, and other components
- Estimating power dissipation to select suitable resistors or heat sinks
- Improving circuit efficiency and ensuring components operate within safe limits