Before you start your project, you need to calculate the size of the roof you intend to cover. The square footage of a roof is normally measured in "squares" of 100 feet
http://www.ehow.com/way_5580726_manysquarefeetb...

100 square feet is called a 'square' Given that, you roof is 36 'squares' Shingle coverage for 20, 25, and 30 year shingles is 3 bundles per square. 40 and 50 year shingles are 4
http://wiki.answers.com/Q/How_many_bundles_of_shin...

A "square" is an area of roof which measures 100 square feet. Thanks
http://www.chacha.com/question/howmanysquarefee...

Actually there are 99.9 square feet in a square of shingles. 33.3 per bundle. EDIT: I have a roofer with 35 years experience sitting two rooms away if you're trying to figure out
http://answers.yahoo.com/question/index?qid=200802...
