Enter the input voltage (volts) and the voltage drop across the resistor (ohms) into the calculator to determine the Zener Voltage.

## Zener Voltage Formula

The following formula is used to calculate the Zener Voltage.

Vz = Vs - Vr

- Where Vz is the Zener Voltage (volts)
- Vs is the input voltage (volts)
- Vr is the voltage drop across the resistor (ohms)

To calculate the Zener voltage, subtract the voltage drop across the resistor from the input voltage.

## How to Calculate Zener Voltage?

The following two example problems outline how to calculate the Zener Voltage.

**Example Problem #1:**

- First, determine the input voltage (volts). In this example, the input voltage (volts) is measured to be 100.
- Next, determine the voltage drop across the resistor (ohms). For this problem, the voltage drop across the resistor (ohms) is calculated to be 30.
- Finally, calculate the Zener Voltage using the formula above:

Vz = Vs – Vr

Inserting the values from above and solving the equation with the imputed values gives:

Vz = 100 – 30 = 70 (volts)

**Example Problem #2: **

Using the same process as example problem 1, we first define the variables outlined by the formula. In this case, the values are:

input voltage (volts) = 145

voltage drop across the resistor (ohms) = 10

Entering these values into the formula above gives :

Vz = 145 – 10 = 135 (volts)