LED Current Limiting Resistor Calculator

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Using the datasheet of the LED and the voltage used to power the LED, this calculator can determine what resistance in series is required to get your LED functioning and prevent it from burning out.

Circuit Values

Enter the values for your circuit below.

Supply Voltage ~V_s~ * V

The voltage from the power supply.

LED forward voltage drop ~V_f~ * V

The LED forward voltage drop is usually found in the datasheet for your LED. If you do not have this value, it can usually be determine used a multimeter "diode" setting. This value will likely be between 1.8 and 3.3 volts. A red LED typically has a forward voltage drop of approximately 1.8 volts, increasing to approximately 3.3 volts in a blue LED as the colors move through the spectrum. If necessary, you can estimate using the following values:

Red or Orange	2.0 V
Yellow	2.1 V
Yellow	2.1 V
Green	2.2 V
Blue or White	3.3 V

LED forward current ~I_f~ * mA

The LED forward current is usually found in the datasheet for your LED.

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