Enter the tap-up percentage (%) and the secondary voltage (volts) into the calculator to determine the Tap Voltage. 

Tap Voltage Formula

The following formula is used to calculate the Tap Voltage. 

Vt = Vs * T /100


  • Where Vt is the Tap Voltage (volts)
  • T is the tap up percentage (%)
  • Vs is the secondary voltage (volts) 

To calculate the Tap voltage, multiply the tap up percentage by the secondary voltage.

How to Calculate Tap Voltage?

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

Example Problem #1:

  1. First, determine the tap up percentage (%). In this example, the tap up percentage (%) is measured to be 50.
  2. Next, determine the secondary voltage (volts). For this problem, the secondary voltage (volts) is calculated to be 4.
  3. Finally, calculate the Tap Voltage using the formula above: 

Vt = Vs * T /100

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

Vt = 4* 50/100 = 2 (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:

tap up percentage (%) = 5

secondary voltage (volts) = 60

Entering these values into the formula or calculator above gives us:: 

Vt = 60 * 5 /100 = 3 (volts)