Enter the LED resistance (ohms), the LED current (amps), and the source voltage (volts) into the calculator to determine the LED Voltage. 

LED Voltage Formula

The following formula is used to calculate the LED Voltage.

Vled = Vs – R*I

  • Where Vled is the LED Voltage (Volts)
  • R is the LED resistance (ohms) 
  • I is the LED current (amps) 
  • Vs is the source voltage (volts) 

How to Calculate LED Voltage?

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

Example Problem #1

  1. First, determine the LED resistance (ohms). In this example, the LED resistance (ohms) is determined to be 16 .
  2. Next, determine the LED current (amps). For this problem, the LED current (amps) is measured to be 7 .
  3. Next, determine the source voltage (volts). In this case, the source voltage (volts) is found to be 2.
  4. Finally, calculate the LED Voltage using the formula above: 

Vled = Vs – R*I

Inserting the values from above into the equation gives: 

Vled = 17 – 7*2 = 3 (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: 

LED resistance (ohms) = 5

LED current (amps) = 4

source voltage (volts) = 1

Entering these given values into the calculator above yields:

Vled = 5 – 4*1 = 1 (Volts)