Free Online LED Resistor Calculator

Free LED Resistor Calculator

What resistor do i need for my led
A Common Resistor

Find Out What Resistor You Need For Your LED

This simple online calculator will show you exactly what sized resistor to use with your LED project. Simply fill out the form and hit "Calculate" and the correct sized resistor will be shown.

Single LED Circuit

This calculator will show you what sized resistor to use for a single LED.

Enter any voltage between 1 and 250 in the first column.
Enter the LED voltage drop (LED voltage) in the second column. This can range from 1 to 100.
Enter the LED current in the third column. This can be between 1 to 900 miliamps.
Hit "Calculate" and get the results

If the results come up negative, then you are using too many LEDs for the voltage supply. You will need to reduce the amount of LEDs or increase the supply voltage.

Series LED Circuit

This calculator will show you what sized resistor to use for a series of LEDs.

Enter any voltage between 1 and 150 in the first column.
Enter the LED voltage drop (LED voltage) in the second column. This can range from 1 to 100.
Enter the LED current in the third column. This can be between 1 to 900 miliamps.
Enter the number of LEDs you want to use in the fourth column. This can be from 2 to 60 LEDs.
Hit "Calculate" and get the results

If the results come up negative, then you are using too many LEDs for the voltage supply. You will need to reduce the amount of LEDs or increase the supply voltage.

For parallel LED circuits, use the series calculator above, but enter only a single row of LEDs. The results will be the same for every parallel row in your circuit. For example, if you want to use 36 LEDs rated at 2.7 volts, and a 12 volt power supply, you would enter only 4 LEDs into the calculator for series circuits. You would then use the same resistor size for every parallel row in the circuit.

For full detailed instructions on How To Make A 120 Volt LED Light Bulb.

Follow this link to Make A 12 Volt LED Light Bulb

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