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Ohm's Law Calculator

Calculate for Current, Voltage, Power, or Resistance

Ohm's Law Calculator for Voltage, Current, Resistance & Power

Our Ohm’s law calculator takes the guesswork out of calculating circuit parameters for electrical power. Whether you're looking to compare voltage and current to find the right power inductor, or to check the voltage of your application against resulting currents for the right switch mode transformer, we have designed this online tool to help you calculate the voltage, current, resistance, or power using only two given parameters.

Scroll down to use the Ohm's law calculator or view calculator tips & features here.

Ohm's Law Calculator Key Features

Want to calculate voltage and current, but don’t have the numbers for resistance? Our Ohm’s law calculator was built to help engineers understand the difference between two parameters without dealing with Excel formulas and spreadsheets. Our calculator helps you solve simple circuits in a quick, efficient way. Please note that you do NOT have to use all the fields provided in this calculator. You need two parameters to return results.

Here are a few of our calculator's key features, along with tips on how to use them.

  • Lock Field Data
    The lock icon featured next to each field will “lock in” the number you placed in that field. By clicking on the lock icon, you are holding that field data in place as you add your other parameters. (i.e. You know your voltage and current numbers should stay the same but want to determine values for resistance and power. )
  • Share Results (Social Media & Share Link)
    After you’ve entered your voltage, current, resistance, or power data, you have the ability to share your results on Facebook, Twitter, or LinkedIn. You may also copy the share link URL and paste it to send others to your results for further collaboration.
  • Download Results (PDF)
    You also have the ability to download your calculations in a free PDF format by clicking the "Download results" button at the bottom of the calculator.


What is Ohm's Law?

What is Ohm’s law? And, what can Ohm’s law be used for?

A German physicist, Georg Ohm, created a formula in 1827 to calculate the relationship between voltage, current, and resistance in an electrical circuit. He was essential in discovering that one volt of electrical current flow through a conductor is needed to press one amp of current through one ohm of resistance.

Ohm’s law comes in handy when measuring resistance. Resistance cannot be calculated in an operating circuit. Instead of turning off the circuit to measure, an engineer can use the Ohm’s law calculator to determine resistance.


How to Calculate Ohm's Law

The standard equation for Ohm’s law is E = I x R.

When broken down, this means voltage = current x resistance, or volts = amps x ohms, or V = A x Ω. Ohm’s law shows the difference between two points on an electrical circuit (E) is equal to the current between those two points (I) and the total resistance between those two points (R). You can use these calculations to validate current levels, voltage drops, and values of circuit components.