I too prefer to add an inch to the finished size (that would mean you cut your squares 4" to get a 3" finished HST). I have done the triangle paper thing, but I hate the price. Someone here posted a link one time to pages of triangle paper that you can print and that is a help.
Now, on my soap box, as has been mentioned -- you cannot count on fabric being 44" (something along the same lines as a 2x4 not measuring 2"x4"). When I calculate fabric I have found that 40" is a good bet -- I have seen some salvages over 1" deep and some fabric when I prewash it shrinks a bit too.