4/12 pitch, multiply by 1.031
A low, walkable roof. A 2,000 sq ft footprint gives about 2,062 sq ft of roof, so roughly 20.6 squares.
Guide
What Is a Roofing Square?
It is the unit every roofing quote is written in, and it is not the same as the square footage of your house.
The definition
One hundred square feet of roof
A roofing square is 100 square feet of roof surface. That is the whole definition. A roof measuring 2,200 square feet is 22 squares, and every contractor you speak to will quote it that way.
The reason it exists is packaging. Asphalt shingles are made and sold around the square, and at three bundles per square for most architectural products the arithmetic on a job site stays simple.
The trap is assuming a roofing square relates to the square footage of your house. It does not. A square is roof surface, and a sloped roof always covers more ground than the footprint beneath it.
The part that catches people
Your roof is bigger than your house
A 2,000 square foot footprint is never 20 squares of roof.
6/12 pitch, multiply by 1.118
The most common pitch on Triangle homes. The same footprint becomes about 2,236 sq ft, or 22.4 squares.
8/12 pitch, multiply by 1.202
Getting steep. Now 2,404 sq ft, or 24 squares, from the identical house.
12/12 pitch, multiply by 1.414
A 45 degree roof. That 2,000 sq ft footprint is 2,828 sq ft of roof, nearly 28.3 squares and about 40% more material.
Do not know your pitch? Work it out with the roof pitch calculator, then feed it into the roofing square calculator.
Working out your own count
Three steps
Measure the footprint
Length times width of the area the roof covers. Include the garage and any additions, because they are roof too.
Multiply by the slope factor
Use the figure for your pitch from the table above. This converts flat ground area into actual roof surface.
Divide by 100, then add waste
That gives squares. Add ten percent on a simple roof, fifteen on one cut up with valleys and dormers.
Reading a quote written in squares
What the number should come with
A quote that says 24 squares and nothing else is not telling you much. What makes it checkable is the detail alongside it: the shingle manufacturer and line, whether the price is a tear-off or an overlay, how many bundles per square that product needs, and what waste allowance is built in.
If two quotes disagree on square count by more than about a square, one of them has measured differently. That is worth asking about before you compare the prices, because you may not be comparing the same roof.
Our cost guide covers what a square typically costs in the Triangle.
Questions
Roofing square questions
What is a roofing square?
One roofing square is 100 square feet of roof surface. It is the unit contractors quote in, so a 2,200 square foot roof is 22 squares.
Why not just quote in square feet?
Habit, mostly, and it keeps the numbers small. Shingles are also packaged around the square, at three bundles per square for most architectural products.
Is a roofing square the same as a square of my house?
No, and this is where people get caught. A square is roof surface, not floor area. A sloped roof always covers more than the footprint underneath it.
How many bundles are in a square?
Three for most architectural shingles. Heavier designer products can run four, so read the wrapper rather than assuming.
How do I work out my own square count?
Take the ground footprint, multiply by the slope factor for your pitch, then divide by 100. The calculator does all three steps.
Does the quote include waste?
It should. Ten percent on a plain gable roof and up to fifteen on one with valleys and dormers, because every cut leaves an offcut.
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