Home > Online Calculation Tools > LED current limiting resistor calculation
Tools Category

LED current limiting resistor calculation

The calculator is an LED light-emitting diode current limiting resistor value calculator, which can calculate the LED current limiting resistance online.

How to calculate the current limiting resistance of LED led?

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

Single LED circuit
Note: Different manufacturers, different color pressure drop is not the same.

Red:2.0-2.2v Yellow:1.8-2.0v

White:3.0-4v Blue:3.0-4v

Green:2.0-2.2v 3.0-3.2v The above is for reference only.

Voltage
  V
LED drop
  V
Required LED current
  mA



Calculating current limiting resistor
  Ω
Closest standard resistance
 
Calculate the resistance power
  W
Safe resistor power
  W
Single led with single resistor
LED series circuit
Several leds in series with one resistor
Voltage
  V
LED drop
  V
Required LED current
  mA
Number of connected LEDs
 



Calculating current limiting resistor
  Ω
Closest standard resistance
 
Calculate the resistance power
  W
Safe resistor power
  W
LED parallel circuit
Several leds connected parallel with one resistor
Voltage
  V
LED drop
  V
Required LED current
  mA
Number of connected LEDs
 



Calculating current limiting resistor
  Ω
Closest standard resistance
 
Calculate the resistance power
  W
Safe resistor power
  W