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Wait...what you need to do is realize you can only run 2 LEDs in series with 5 volts. If you try that, the calculator will probably say, "48 ohms". I suspect you are using the MAXIMUM RATED CURRENT for the LEDs, so use the next higher value resistor, like 56 ohms, 1/8th or 1/4 watt. Then make 3 sets of 2 LEDs and a resistor.
First the arrangement pictured is not very good as to LEDs. You don't want to parallel two LEDs with a single series resistor. Before we even worry about that there is no way to answer your question. You have not told us what the LED characteristics are for the LEDs you have. For example red, green and blue LEDs have different forward voltage drops and current. That is also true of LEDs the same color. You would need to provide the forward voltage and current for the specific LEDs you have. Too little current in a LED circuit and it is dim, too much and it is real bright for a real short time.
LED calculatoirs are fine but you need to know what to insert for values like forward voltage and current. Checkmate!
He is using a PARALLEL calculator. The math is correct. If you run those PARALLEL you will need at a minimum a 18 ohm 1 watt resistor.
I tend to believe that bigger is better with heat dissipation and would go with a 2 watt resistor.
However; I agree with "#12" that it seems that you are probably looking at the MAX current for those LEDs and it might not be the best idea. Step down to 20 mA for each and you're looking at a 27 ohm resistor 1 watt resistor. Once again go for a 2 watt resistor for better heat dissipation.
Most importantly: I would double-check your LED specs. RED leds are typically 2.3v and most BLUE or WHITE are 3.5v.
I hope you haven't confused "reverse voltage" with what you get out of an x-box 360!
The reverse voltage of an LED doesn't really matter because you don't operate them in reverse.
If the x-box provides 5 volts, you are O.K.
NO. Each string starts at the x-box 5 volts, then goes to one resistor, then goes to one LED, then goes to one more LED, then a ground wire. It's called a "series" string. You need to make 3 series strings.
Putting the LEDs in paralell doesn't work because one will steal all the current and burn up while the rest go hungry. When the first one burns up, the next most sensitive LED will burn up, and then the next. (Trying to use simple words so the translator works better.)
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