Roofing: How many squares of Shingles needed?

I have a 810 square foot roof (27' X 30') which includes a 1' overhang.
How many squares am I going to need for a 4 /12 pitch roof.
Thank you,
John

3 bundles of 3-tab shingles cover approximately 100 square feet, so my estimate would be 25 bundles, minimum. You'll want to have some extra, espically if you are doing a ridge vent. I would pick up 27 or 28 bundles, but that's just a guess.

I have a 810 square foot roof (27' X 30') which includes a 1' overhang.

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If I am reading what you typed right the 27' in the width of the garage x 30' long, and then a 1' overhang on all 4 sides. So if the gable end is on the 27' side and with adding 1' for an overhang, that will make one side of your roof 15.2' approx x 32' long which would be almost 489 square foot. Divide that by 100 and that gives you 4.89 squares of shingles per side or 9.78 square total, so figure 10 square for roofing. For ridge cap, you get 15" of ridge cap per shingle (if that is the way you are going to go) So 32' x 12=384" of ridge divided by 5 (number of inches per ridge shingle) =77 pieces of tabs for ridge cap, so there are approx 25 shingles per bundle x 3 per shingle means you need 1 bundle for ridge cap. And you always want to have a couple of extra bundles on hand for replacement, etc. So if I were you I would pick up 12 square to start with as you need a starter course on each side and you will have some scrap on your ends.

Kevin

Take your roof footprint area and multiply by the roof pitch factor (1.06 for a 4/12 roof). Divide that by the actual coverage of the shingles you're using. Average three tabs are usually about 3 bundles per square. Architectural shingles will need up to 6 or 7 bundles per square. Then you need to add in starter strip, ridge / hip shingles, etc.

In your case:
810 sf x 1.06 = 859 sf of roof = 8.6 square

For standard 3 tab shingles: 8.6 square x 3 bundles / square = 26 bundles

For an architectural shingle: 8.6 square x 6 bundles / square = 52 bundles

Don't forget to buy a couple of extra bundles from the same prodcution run to make the inevitable future repair.

EDIT: If your garage has a hip roof, you will need to more shingles than a standard gable roof.

I really appreciate everyone's reply.
I know it takes some time to do the calculations, so again I "thank you", as this info gives me a much better feeling of what I have (cost wise) in front of me.
John