Electronics, programming & other stuff

LED resistor calculator

Given the type of LED (nominal voltage and current) and the supply voltage, this page calculates the required resistor to connect the LED safely, as well as the required power that it will dissipate.


Commercial value

A safety margin is advised, specially if the power is close to 1/8W (125mW) or 1/4W (250mW)

LED voltages (typical values):

  • Red: 1.8 V to 2.2 V
  • Orange: 2.1 V to 2.2 V
  • Yellow: 2.1 V to 2.4 V
  • Green: 2 V to 3.5 V
  • Blue: 3.5 V to 3.8 V
  • White: 3.6 V

LED currents (typical values):

  • Standard: 20mA
  • High intensity Blue: 30mA
  • Indicator LEDs: 15mA


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