Current Limiting Resistor Calculator

A current limiting resistor regulates and reduces the current in a circuit. This equation and calculator helps determine the value of the resistor to add to a light-emitting diode (LED) so that it can limit the current moving through the LED. The calculation also determines how much power the LED consumes.

Inputs

Maximum input voltage:

Minimum input slet:

Output voltage:

Maximum load current:

Outputs:

Current limiting resistor:

Power rating:

Zener diode:

Power rating:

Equations

Utilizing the basic principles of Ohm’s law provides this formula:

R = Resistor

Vs = Supply Voltage

Iled = LED Current

Vled = LED Voltage Drop

X = Number of LEDs in a series

Application

If too much current flows through an LED, it could be destroyed. And, if there is too little current flowing through the LED, the resulting light intensity may be inadequate. In order to provide the correct amount of LED current, you must calculate the required resistance.