led calculations

[atomicareprise]

i use this link http://ledcalc.com/

supply voltage:i did the direct contacts in the speaker so i'm supposing 3.6v..
                      5v if i use lm386...is this correct

voltage drop across led: 3.3(blue)

desired led current: 20mA...is this correct

how many leds: 12

18 ohms is what comes out...

just need your opinion guys if i'm heading on the right track...

[Max_Kreeger]

Or you could use this formula V=I.R

V= Volts
I = Current (amps)
R =  Resist (Ohms)

So e.g.:

3.6= 20.R
R= 3.6/20
R= .18

So yeah looks right. I'm just not sure about the desired led current.
Sorry.