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  
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

.:Single led  
Exact calculated resistance
OHMS
Nearest higher rated resistor
Wattage recommendation for the resistor
WATTS
Circuit's current consumption
mA
Actual LED Current
mA
Power dissipated by the LED
mW
Power dissipated by the Resistor
mW 
.:Leds in series  
Exact calculated resistance
OHMS
Nearest higher rated resistor
Wattage recommendation for the resistor
WATTS
Circuit's current consumption
mA
Actual Single LED Current
mA
Power dissipated by the LED
mW
Power dissipated by the Resistor
mW 
.:Leds in parallel  
Exact calculated resistance
OHMS
Nearest higher rated resistor
Wattage recommendation for the resistor
WATTS
Circuit's current consumption
mA
Actual single LED Current
mA
Power dissipated by the LED
mW
Power dissipated by the Resistor
mW 