About LED Resistor Calculator

The LED Resistor Calculator helps you determine the resistor value required to limit current in an LED circuit. By entering the supply voltage, LED forward voltage, and desired current, the calculator uses Ohm’s Law to compute the resistor value. This ensures safe and efficient operation of your LED.

Formula

The resistor value (\( R \)) is calculated using the formula:

\[
R = \frac{V_{\text{supply}} – V_{\text{forward}}}{I_{\text{LED}}}
\]

Where:

• \( R \): Resistor value in Ohms (\(\Omega\))
• \( V_{\text{supply}} \): Supply voltage in Volts (V)
• \( V_{\text{forward}} \): LED forward voltage in Volts (V)
• \( I_{\text{LED}} \): LED current in Amperes (A)

Example Calculations

Let’s calculate the resistor value for the following setup:

• Supply Voltage (\( V_{\text{supply}} \)): 12V
• LED Forward Voltage (\( V_{\text{forward}} \)): 2V
• LED Current (\( I_{\text{LED}} \)): 20mA (0.02A)

Step 1: Calculate the voltage drop across the resistor:
\[V_{\text{drop}} = V_{\text{supply}} – V_{\text{forward}} = 12 – 2 = 10 \, \text{V}\]

Step 2: Calculate the resistor value:
\[R = \frac{V_{\text{drop}}}{I_{\text{LED}}} = \frac{10}{0.02} = 500 \, \Omega\]

Result: The required resistor value is \( 500 \, \Omega \).