The calculator is an LED light-emitting diode current limiting resistor value calculator, which can calculate the LED current limiting resistance online.
LED current limiting resistor calculation formula: current limiting resistor Ω = (supply voltage V - LED cut-in voltage V) / current limiting current A
Suppose you buy an LED with a cut-in voltage of 3.2V, a current-limiting current of 20mA, and a vehicle power supply voltage of 12V. The formula is (12V-3.2V) / 0.02A = 440.
If three resistors are connected in series, then the resistance value of each resistor is: (12V-3.2V*3) / 0.02A = 120Ω
And so on