LED Resistor Value – For your LED Projects

We need correct LED resistor value to ensure that the LED operates at the desired brightness level and doesn’t get damaged by excessive series current though it. In this article, we will explore the resistor values for different color LEDs for different common voltage values.

These values below are calculated based on generally documented forward voltages for the Red (R)- 2.0 Volts, Green (G)- 2.5 Volts,  Blue (B)- 3.3 Volts, White (W)- 3.5 Volts, LEDs and forward current @ 20mA for maximum brightness. These values are calculated and tested for working within safe operating points and can be used for any circuit and any projects.

First select the supply voltage or Source voltage (Vs). Now pick the corresponding optimal value of (R) Resistor. You can choose any resistor value from minimum, maximum and optimal value, optimal being recommended.

Input Voltage (Vs)	LED color	Min. Value of Resistor	Optimal Resistor (R) @20mA	Max. Value of resistor
3V	Red	47 Ω	51 Ω	56 Ω
	Green	22 Ω	24 Ω	27 Ω
	Blue	-	-	-
	White	-	-	-
3.7V	Red	75 Ω	82 Ω	91 Ω
	Green	56 Ω	62 Ω	68 Ω
	Blue	-	20 Ω	22 Ω
	White	-	10 Ω	-
4.2V	Red	100 Ω	110 Ω	120 Ω
	Green	75 Ω	82 Ω	91 Ω
	Blue	43 Ω	47 Ω	51 Ω
	White	33 Ω	36 Ω	39 Ω
5V	Red	130 Ω	150 Ω	160 Ω
	Green	110 Ω	120 Ω	130 Ω
	Blue	75 Ω	82 Ω	91 Ω
	White	68 Ω	75 Ω	82 Ω
6V	Red	180 Ω	200 Ω	220 Ω
	Green	160 Ω	180 Ω	200 Ω
	Blue	120 Ω	130 Ω	150 Ω
	White	110 Ω	120 Ω	130 Ω
9V	Red	330 Ω	360 Ω	390 Ω
	Green	300 Ω	330 Ω	360 Ω
	Blue	240 Ω	270 Ω	300 Ω
	White	240 Ω	270 Ω	300 Ω
12V	Red	470 Ω	510 Ω	560 Ω
	Green	430 Ω	470 Ω	510 Ω
	Blue	390 Ω	430 Ω	470 Ω
	White	390 Ω	430 Ω	470 Ω
24V	Red	1 KΩ	1.1 KΩ	1.2 KΩ
	Green	1 KΩ	1.1 KΩ	1.2 KΩ
	Blue	910 Ω	1.0 kΩ	1.1 KΩ
	White	910 Ω	1.0 kΩ	1.1 KΩ

 

Check Online LED Resistor Calculator here!

 

LED Life and Current

It’s important to understand the relation between LED life and current while selecting the resistor’s values for an LED. More than optimal current through the LED shortens the operating life of the LED.
Also over-current/ over-voltage causes immediate permanent damage and fuses the diode permanently. On the contrary, insufficient current or you can say under-current can result in a dimmed LED or one that does not glow at all.

Optimal Value and Efficiency

By selecting the optimal LED resistor value, it can help to increase the efficiency and minimize power consumption. This is very important to choose a LED resistor value that limits the extra current in the case if the circuit is portable and battery operated. This can help to extend the life of the device and reduce charging recharging of the circuit.

Below values are for near optimal values for working in highly efficient ways. It saves a lot of power of battery operated devices as it gives near maximum brightness at lower current which is helpful in LED indicator applications.

These LED resistor chart values below are calculated based on generally documented forward voltages for the Red (R)- 2.0 Volts, Green (G)- 2.5 Volts,  Blue (B)- 3.3 Volts, White (W)- 3.5 Volts LEDs and forward current @ 15mA for near maximum brightness.

First select the supply voltage or Source voltage (Vs). Now pick the corresponding optimal value of (R) Resistor. You can choose any resistor value from minimum, maximum and optimal value, optimal being recommended.

Input Voltage	LED color	Min. Value of Resistor	Optimal Value of Resistor @15mA	Max. Value of resistor
3V	R	62 Ω	68 Ω	65 Ω
	G	30 Ω	33 Ω	36 Ω
	B	-	-	-
	W	-	-	-
3.7V	R	100 Ω	110 Ω	120 Ω
	G	75 Ω	82 Ω	91 Ω
	B	24 Ω	27 Ω	30 Ω
	W	10 Ω	13 Ω	15 Ω
4.2V	R	130 Ω	150 Ω	160 Ω
	G	100 Ω	110 Ω	120 Ω
	B	56 Ω	62 Ω	68 Ω
	W	43 Ω	47 Ω	51 Ω
5V	R	180 Ω	200 Ω	220 Ω
	G	150 Ω	160 Ω	180 Ω
	B	100 Ω	110 Ω	120 Ω
	W	91 Ω	100 Ω	110 Ω
6V	R	240 Ω	270 Ω	300 Ω
	G	220 Ω	240 Ω	270 Ω
	B	160 Ω	180 Ω	200 Ω
	W	150 Ω	160 Ω	180 Ω
9V	R	430 Ω	470 Ω	510 Ω
	G	390 Ω	430 Ω	470 Ω
	B	360 Ω	390 Ω	430 Ω
	W	330 Ω	360 Ω	390 Ω
12V	R	620 Ω	680 Ω	750 Ω
	G	560 Ω	620 Ω	680 Ω
	B	510 Ω	560 Ω	620 Ω
	W	510 Ω	560 Ω	620 Ω
24V	R	1.3 KΩ	1.5 KΩ	1.6 KΩ
	G	1.3 KΩ	1.5 KΩ	1.6 KΩ
	B	1.2 KΩ	1.3 KΩ	1.5 KΩ
	W	1.2 KΩ	1.3 KΩ	1.5 KΩ

By selecting the correct resistor values, you can ensure that your LED circuit operates at the desired brightness level, is efficient, and offers the minimal power dissipation. And thus while designing an LED circuit for critical applications, be sure to refer to the datasheet for specific LED to determine the appropriate operating values.