Free tool

Ohm's Law Calculator

Enter two quantities and get the third one instantly. A useful tool for validating prototypes, checking measurements and solving quick electronics questions.

Tools

Calculate voltage, current or resistance in one place

You only need to enter two values and the calculator fills in the third using the relation V = I x R. You can work with volts or millivolts, amps or milliamps, and resistance in ohms or kilo-ohms.

Ohm's Law Calculator

Fill in exactly two fields. The tool detects the missing quantity and calculates it automatically.

Enter exactly two valid values to calculate the missing quantity.
Result--The calculator will show the calculated value and the formula used.

Notes on use

Ohm's law is one of the foundations of resistive-circuit analysis and helps you validate prototypes quickly.

Key formulas
  • Voltage: V = I x R
  • Current: I = V / R
  • Resistance: R = V / I
When to use it
  • Verificar caidas de tension en prototipos.
  • Comprobar consumo en ramas resistivas sencillas.
  • Dimensionar resistencias de limitacion o carga.

Quick guide

How to apply Ohm's law during assembly, testing and debugging

Ohm's law directly links voltage, current and resistance. In a technical review it helps you check whether a measured value makes sense and whether the chosen components are operating within the expected range.

Quick read

  • Si conoces voltaje y corriente, obtienes resistencia al instante.
  • Si conoces voltaje y resistencia, puedes estimar consumo.
  • Si conoces corriente y resistencia, obtienes la tension necesaria.
  • Antes de calcular, convierte todas las unidades a su escala correcta.

Main relation

Voltage is proportional to the current flowing through the circuit and to the circuit resistance.

V = I x R

Useful rearrangements

These direct rearrangements let you move from a bench measurement to the quantity you still need.

I = V / R | R = V / I

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FAQ

Frequently asked questions

A short reference for the most common questions when you use Ohm's law in basic electronics or during prototype validation.

What does this tool calculate?

It calculates the missing quantity among voltage, current and resistance when you enter exactly two valid values.

Can I use milliamps or millivolts?

Yes. The calculator automatically converts millivolts and milliamps to the base scale before running the calculation.

Does it work for complex circuits?

It is more useful for resistive sections or quick checks. In more complex circuits, you should also review the context of the other components.

Is the calculator free?

Yes. You can use it online without registering or installing anything.

Next step

Need help with the electronic design of your project?

If you are developing a product and need support with electronics, PCBs, firmware or technical validation, we can review your case and point you in the right direction.

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