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:

  1. First, determine the input voltage (volts). In this example, the input voltage (volts) is measured to be 100.
  2. Next, determine the voltage drop across the resistor (ohms). For this problem, the voltage drop across the resistor (ohms) is calculated to be 30.
  3. 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)

FAQ

What is a Zener Voltage?

Zener voltage refers to the voltage at which a Zener diode, a type of semiconductor device, allows current to flow in the reverse direction when a certain voltage threshold is exceeded. It is used for voltage regulation in circuits.

How does a Zener diode differ from a regular diode?

While both Zener and regular diodes allow current to flow in one direction under normal operation, a Zener diode is specifically designed to also safely allow current to flow in the reverse direction when the voltage exceeds its Zener voltage, without damaging the diode. Regular diodes, on the other hand, are not designed for reverse breakdown operation.

Why is calculating Zener Voltage important in electrical circuits?

Calculating the Zener voltage is crucial for designing circuits that require stable voltage supply regardless of variations in load current or input voltage. It helps in selecting the right Zener diode to ensure it operates in its Zener breakdown region for effective voltage regulation.