LED Resistor Calculator
Calculate the resistance needs for a single LED.
Usually: Red (2.0V), Blue/White (3.3V)
Why do LEDs need resistors?
LEDs (Light Emitting Diodes) are current-driven devices with low internal resistance. Without a resistor to limit current, an LED connected directly to a voltage source will draw excessive current and burn out almost instantly.
Formula
R = (Vs - Vf) / If
Where Vs is Source Voltage, Vf is Forward Voltage drop of the LED, and If is the desired LED current.