Ohm's Law Calculator
Calculate voltage, current, resistance and power — enter any two values.
Ohm's Law states V = I × R (voltage equals current times resistance) and P = V × I (power equals voltage times current). Enter any two of the three values and the remaining one will be calculated automatically.
What is Ohm's Law Calculator?
Ohm's Law Calculator determines voltage, current, resistance, and power from any two known values using the fundamental electrical relationship V = I x R.
Ohm's Law is one of the most basic principles in electrical engineering and is essential for circuit design, troubleshooting, and safety calculations.
How does the Ohm's Law Calculator work?
Voltage (V) equals current (I) multiplied by resistance (R). If you know any two values, the third can be calculated directly.
Power (P) is the product of voltage and current, measured in watts. It represents the rate at which electrical energy is consumed or produced.
How to use the Ohm's Law Calculator?
- Enter any two of the three values: voltage, current, or resistance.
- The calculator automatically computes the third value and the resulting power.
- Leave one field at zero to let the calculator solve for it from the other two inputs.
- Review all four results — voltage, current, resistance, and power — on the right side.
Example
Try the calculator with your own numbers
- Enter your values in the input fields above.
- Adjust the values to match your situation.
- The result updates instantly as you change the inputs.
Benefits of using the Ohm's Law Calculator
- Instantly solves for any missing electrical quantity from two known values.
- Also calculates power consumption, making it useful for sizing components and fuses.
- A fundamental reference tool for students, electricians, and electronics hobbyists.
Who should use the Ohm's Law Calculator?
- Students and professionals who need fast, accurate results.
- Anyone who wants to verify a manual calculation.
- People who prefer a quick answer over working it out by hand.
Tips for getting the most out of the Ohm's Law Calculator
- Double-check the values you enter before relying on the result.
- Use the calculator to verify manual calculations or estimates.
- Bookmark the page if you use it regularly.
Frequently Asked Questions
What if I enter all three values?
The calculator resolves conflicts using a priority order: if both voltage and current are positive, resistance is recalculated from them. Similarly for other combinations.
Is this applicable to AC circuits?
Ohm's Law in this form (V = IR) applies to DC circuits and resistive AC circuits. For AC circuits with reactance (capacitors or inductors), impedance (Z) replaces resistance and the formula becomes V = I x Z.
What does power tell me about a circuit?
Power indicates how much energy the circuit consumes per unit time. It helps determine wire gauge, fuse ratings, and whether a power supply can handle the load.
This calculator gives you fast, reliable answers whenever you need them. Try it now and keep it handy for future calculations.
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