Current Limiting Resistor Calculator for Leds

Some good values to try:

As supply voltage:
 For molex: 5, 7 and 12 volts
 Batteries: 1.5 and 9 volts

As led forward voltages:
 Red and green: 2 volts
 Blue and white: 3.0 - 3.5 volts

Led current:
 20mA will work for most regular leds.
 Superbright leds can go from 30mA up to several amps.

The Guru  -  Single led  -  Series leds  -  Parallel leds


.:GURU

Supply Voltage
  VOLTS
Voltage Drop Across LED
  VOLTS
Desired LED Current
  MILLIAMPS
How many leds connected
 

 
Guru suggestion
Exact calculated resistance
  OHMS
Nearest higher rated resistor
 
Wattage recommendation for the resistor
  WATTS
Circuit's total current consumption
  mA
Actual Single LED Current
  mA
Power dissipated by the LED
  mW
Power dissipated by the Resistor
  mW
R1
Exact calculated resistance
  OHMS
Nearest higher rated resistor
 
Wattage recommendation for the resistor
  WATTS
 
Actual Single LED Current
  mA
Power dissipated by the LED
  mW
Power dissipated by the Resistor
  mW
R2