LED Current Limiting Resistor Calculator

Calculate the resistor value needed for an LED circuit using:
$R = \frac{V_{supply} - V_{LED}}{I_{LED}}$

* Enter the supply voltage (V), LED forward voltage (V), and LED current (mA).

Step 1: Enter Circuit Parameters

Supply Voltage,

V_{supply}

(V):

Example: 9 V battery

LED Forward Voltage,

V_{LED}

(V):

Example: 2 V for a red LED

LED Current,

I_{LED}

(mA):

Example: 20 mA