Roof Squares Chart by House Size and Pitch
Fifteen common footprints against six pitches, so you can find a house roughly the size of the one in front of you and see the squares before you measure anything.
A roofing square is 100 square feet of roof surface, and a bundle of architectural shingles covers about a third of one. The number that matters is therefore squares, not square feet, and it is the number a supply house wants when you call an order in.
Every figure in this table came out of the roofing calculator with a 10 percent waste allowance already applied, which is the normal allowance on a simple gable. A cut up roof with valleys, dormers and hips wants 15 percent and sometimes more.
Roofing squares by footprint and pitch
| Footprint | Ground area | 3/12 | 4/12 | 6/12 | 8/12 | 10/12 | 12/12 |
|---|---|---|---|---|---|---|---|
| 20 x 30 ft | 600 sq ft | 6.8 | 7 | 7.4 | 7.9 | 8.6 | 9.3 |
| 22 x 24 ft | 528 sq ft | 6 | 6.1 | 6.5 | 7 | 7.6 | 8.2 |
| 24 x 30 ft | 720 sq ft | 8.2 | 8.3 | 8.9 | 9.5 | 10.3 | 11.2 |
| 24 x 36 ft | 864 sq ft | 9.8 | 10 | 10.6 | 11.4 | 12.4 | 13.4 |
| 24 x 40 ft | 960 sq ft | 10.9 | 11.1 | 11.8 | 12.7 | 13.7 | 14.9 |
| 26 x 40 ft | 1,040 sq ft | 11.8 | 12.1 | 12.8 | 13.7 | 14.9 | 16.2 |
| 28 x 40 ft | 1,120 sq ft | 12.7 | 13 | 13.8 | 14.8 | 16 | 17.4 |
| 30 x 40 ft | 1,200 sq ft | 13.6 | 13.9 | 14.8 | 15.9 | 17.2 | 18.7 |
| 30 x 50 ft | 1,500 sq ft | 17 | 17.4 | 18.4 | 19.8 | 21.5 | 23.3 |
| 32 x 48 ft | 1,536 sq ft | 17.4 | 17.8 | 18.9 | 20.3 | 22 | 23.9 |
| 36 x 48 ft | 1,728 sq ft | 19.6 | 20 | 21.3 | 22.8 | 24.7 | 26.9 |
| 40 x 50 ft | 2,000 sq ft | 22.7 | 23.2 | 24.6 | 26.4 | 28.6 | 31.1 |
| 40 x 60 ft | 2,400 sq ft | 27.2 | 27.8 | 29.5 | 31.7 | 34.4 | 37.3 |
| 40 x 80 ft | 3,200 sq ft | 36.3 | 37.1 | 39.4 | 42.3 | 45.8 | 49.8 |
| 50 x 60 ft | 3,000 sq ft | 34 | 34.8 | 36.9 | 39.7 | 43 | 46.7 |
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The roofing calculator takes your own measurements and returns the number for your job, plus the material list as a printable document. Every cell in the table above came out of that same calculator, run at build time.
Footprint is not roof area, and the gap grows with pitch
Read one row across and the whole point of the table shows up. The same house needs meaningfully more material at 12/12 than at 3/12, and nothing about the floor plan changed. What changed is that the roof plane got longer while the shadow it casts stayed the same size.
If you are bidding off a satellite image or a plot plan, you are looking at the ground area column. Everything to the right of it is the actual roof.
What waste allowance to use
Ten percent, which is what this table uses, covers starter course, ridge, and the offcuts on a simple gable roof with two planes. Fifteen percent is the honest number for a hip roof, and a roof with valleys, multiple dormers or a lot of flashing detail can run past that.
Waste is not just shingles. It is the reason the second delivery costs more than the first one did, so err toward the higher allowance on anything complicated.
Take the whole material list, not just the squares
Squares get you the shingles. The roofing calculator also gives the underlayment rolls, the starter, the ridge cap, the drip edge and the nails for the same roof, which is the list that actually stops a second trip.
The ridge cap figure moves with the ridge length rather than the area, so measure the ridge separately on anything that is not a plain gable.
Questions people ask
How many squares is a 30 by 40 roof?
Around 14 to 17 squares depending on the pitch, with waste. The ground area is 1,200 square feet, which is 12 squares flat, and every pitch adds to it. Find the 30 x 40 row above and read across to the pitch you have.
How many bundles of shingles are in a square?
Three, for nearly all three tab and architectural shingles sold in the United States. Heavier designer and luxury shingles run four or five bundles to the square, and the wrapper says which.
Does this include the garage or a porch roof?
No. Each row is one rectangle. Add the garage and any porch or bay as their own rectangle and add the squares together, which is what the roofing calculator does when you run it twice.
Why does my supplier quote in squares but sell in bundles?
Because coverage is a property of the roof and packaging is a property of the shingle. Order in squares, confirm the bundle count on the delivery ticket, and check that the bundles per square on the wrapper match what was quoted.