LFM

LED series resistor

An LED needs a series resistor to limit its current to a safe level. Set the supply voltage, the LED color, and a resistor value, then read the current through the LED and whether it lands in the 10 to 20 mA operating range.

Supply voltage
LED color
Series resistor
Ω
Select supply, LED color, and resistor, then press Calculate.

LED schematic symbol

K A
Red
2.0 V
Orange
2.1 V
Yellow
2.3 V
Green
2.3 V
Blue
3.3 V
White
3.6 V