Enter current (I) and resistance (R) to calculate voltage across a passive resistor, or select another known pair. The calculator also supports a loaded resistive divider and RMS/peak conversion with a stated waveform assumption.

Voltage Formula

V = I \times 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 the volt. 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 points across a device, and the voltage drop across the device is known as the difference. When you use one of these reference points as ground, the voltmeter 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

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 are needed in order to calculate the voltage.
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.
The next step is to calculate the resistance
As with the current, this is commonly done empirically. We will assume the value to be 10 ohms.
Finally, enter the information into the formula or calculator
V=I*R = 1000 * 10 = 10,000 volts
Analyze the results
Analyzing the results to check for accuracy and mistakes is the last step in every scientific calculation.