Enter the total emf (volts), the current (amps), and the resistance (ohms) into the calculator to determine the Terminal Voltage. 

Terminal Voltage Formula

The following formula is used to calculate the Terminal Voltage.

Vt = emf - I * R
  • Where Vt is the Terminal Voltage (volts)
  • emf is the total emf (volts) 
  • I is the current (amps) 
  • R is the resistance (ohms) 

To calculate terminal voltage, subtract the product of the current and the resistance from the total emf.

How to Calculate Terminal Voltage?

The following example problems outline how to calculate the Terminal Voltage.

Example Problem #1

  1. First, determine the total emf (volts). In this example, the total emf (volts) is determined to be 100 .
  2. Next, determine the current (amps). For this problem, the current (amps) is measured to be 5 .
  3. Next, determine the resistance (ohms). In this case, the resistance (ohms) is found to be 3.
  4. Finally, calculate the Terminal Voltage using the formula above: 

Vt = emf – I * R

Inserting the values from above into the equation gives: 

Vt = 100 – 5 * 3 = 85 (volts)

Example Problem #2

Using the same method as above, determine the variables required by the equation. For this example problem, these are provided as follows: 

total emf (volts) = 150

current (amps) = 2

resistance (ohms) = 20

Entering these given values into the calculator above yields:

Vt = 150 – 2 * 20 = 110 (volts)