Sound deadening..how much?

I'm looking into sound deadening behind my rear seats and all 4 doors..

How many sq feet should I buy? I'm on a little budget so I didn't want to overbuy.

 

http://www.tacomaworld.com/forum/audio-video/33862-dynamat-poll-yes-no-if-so-how-much.html

 

The exact answer you're looking for is this...
1) Find the square footage of the area you'd like to cover. Write this number down.
2) Using some sort of online conversion tool convert this into square inches.
3) Then divide this number by 144. That will be how many square feet you need to buy.

 

times your length times width for all your dimension then add them all up and divid by the 144 to get the sq ft you need.

example

doors 24x36x2=3456
floor 48x48=2304
backwall 50x20= 1000
ceiling 48x36=1728

add it all up 8488 divide by 144(12x12 {one sqft.})
8488/144= 58.94 or about 60 sqft