You would have to estimate each runs lentgh and then multiple it by the number of runs. I dont see how you could have a magic formula based on sq feet of house. You just want to get in the ballpark and have a source close by for additional rolls. A lot depends on where you media closet and alarm panel etc are.
For most of these cables, small rolls of not efficient so your goal is only to get to the nearest roll. For the cheaper cables that doesn't even matter that much. Cat6 is I think $60 for 1000 feet of .05 a foot or $3.00 for a 50 foot run. No worries if you are off box on that..
I did some super rough estimates when I did mine but mostly what I did was start with 300 foot rolls of my more expensive/harder to get cable and ran that first. That way if I needed another roll I could get more while I did the rest of cat5/alarm wire.
I did my mini-rjb and dual coax/cat5 combos first. I ran one of each to each TV... If I were doing this again I would consider another two cat5s at least. I was going to cancel the coax but directv has some moca hardware which is basically a mini settop box that will fit behind the TV. Also you can get coax to RCA ends and use the coax as a RCA.
This is what I ran to each TV(plus 1 HDMI), but I think I got my cables on ebay. If doing again I would also consider more HDMI as HDMI cable is cheaper then cat5 balauns though they are getting cheaper.
This is my 'most expensive cable', the only one that I really estimated
http://cableorganizer.com/cables/mini-rgb-...ideo-cable.html
http://www.smarthome.com/868261J/2-Cat-5e-...ax-Cable/p.aspx
I did some super rough estimates using this simple formula.
10' from closet to ceiling
+ distance across ceiling. I made guesstimates based on plans for differnt rooms
10' from ceiling back down wall
+10 more feet if on the second floor.
For my HDMI cables I actually drilled the holes, pulled string, pulled string out and measured it with 100 foot tape measure. The reason for that is you dont field terminate it..
*** DONT FORGET CONDUIT **** Orange smurf tub for each TV drop up to attic or down to basement.. Then a big conduit from attic to basement or media closet.. No matter how well you plan you will miss a wire.
I just busted holes in my new babies room to run some extra wires.. I would easily have paid $10 extra for the low voltage conduit to have been at that drop rather then cut open the walls/ceiling..