Speaker wire gauge

Here is the simplest calculator I found.
http://home.hiwaay.net/~rgs/awgcalculator.html
Not many brain cells needed for this LOL

Or you can calculate by this method:
Double the number of speakers in your system.
Add your age.
Subtract number of cars owned.
Add the temperature of your listening room.
Subtract the humidity of your listening room.
Add your zip code.
Subtract your area code.
Check Al's link (above)

I like Xti16's method the best. I thought I favored Audiofeil's, but I don't understand why you have to include your zip code.