Enter the current (I) and the resistance (R) of a system to calculate the voltage running across a conductor. The equation is based on Ohm’s Law.

Voltage Formula

V = I  * R
  • Where V is the voltage
  • I is the current
  • R is the resistance

To calculate voltage, multiply the current by the resistance.

Voltage Definition

Voltage is known as the electric potential difference between two points. The Si unit for voltage is volts. The difference in electrical potential is oftentimes caused by electric charge, electric current, or magnetic fields. Sometimes, it’s decided by all three of those parameters.

How is voltage measured?

To measure voltage a voltmeter is used. This is connected to two opposite points along with a device, and the voltage drop across the device is known as the difference. When using one of these reference points as ground, it provides the total voltage at that point.

How to calculate voltage

The following example will go through the process of how you can calculate the voltage between two points.

How to calculate voltage

  1. First, analyze the formula above to determine what values we must measure in order to calculate voltage

    It can be seen from the formula that both the current traveling between two points and the resistance is needed in order to calculate the voltage.

  2. Next, you must measure the current traveling between the points.

    This can be done either empirically or mathematically, for this example we will assume the current to be 1000 amps.

  3. The next step is to calculate the resistance

    As is with the current, this is commonly done empirically. We will assume the value to be 10 ohms.

  4. Finally, enter the information into the formula or calculator

    V=I*R = 1000 * 10 = 10,000 Volts

  5. Analyze the results

    Analyzing the results to check for accuracy and mistakes is the last step in every scientific calculation.