How to Calculate Roofing Squares from Square Footage?

When planning a new roof or estimating materials, one of the first things you’ll need to know is how many roofing squares your project requires. Roofing contractors commonly use “squares” instead of square feet to simplify estimates and pricing.

If you’ve ever wondered how to convert square footage into roofing squares, this guide explains everything — with examples and formulas included.

What Is a Roofing Square?

A roofing square is a standard unit of measurement in the roofing industry.
1 roofing square = 100 square feet of roof area.

So, if your roof covers 2,000 square feet, that equals 20 roofing squares.

Formula to Calculate Roofing Squares from Square Footage

The formula is very simple:

$Roofing Squares = \frac{Total Roof Area (sq. ft.)}{100}$

Explanation:

Divide your total roof area (in square feet) by 100 because one roofing square equals 100 sq. ft.

Example 1: Simple Roof

Let’s say your roof area is 2,000 sq. ft.

$Roofing Squares = \frac{2000}{100} = 20$

Result:
You’ll need 20 roofing squares.

Example 2: Roof with Slope Factor

If your roof has a slope (pitch), you’ll need to adjust the area because a sloped roof covers more surface than a flat one.

You can use a slope multiplier to find the actual roof area.

$Total Roof Area = Ground Area \times Slope Multiplier$

Slope multipliers for common pitches:

Roof Pitch	Slope Multiplier
4/12	1.054
6/12	1.118
8/12	1.202
10/12	1.305

Example:
Your home’s ground area is 1,800 sq. ft., and the roof pitch is 6/12.

$Total Roof Area = 1800 \times 1.118 = 2012.4$

Now, convert this to roofing squares:

$Roofing Squares = \frac{2012.4}{100} = 20.12$

Result:
You’ll need about 21 roofing squares (always round up).

Including a Waste Factor

When installing shingles, there’s always some waste due to cutting, overlapping, and fitting around edges and ridges.
Roofers usually add 10% to 15% extra shingles for waste.

$Total Squares (with Waste) = Roofing Squares \times (1 + Waste Percentage)$

Example with Waste:

$Total Squares (with Waste) = 20.12 \times (1 + 0.10) = 20.12 \times 1.10 = 22.13$

Result:
Order about 22 roofing squares to cover waste and ensure full coverage.

Quick Reference Chart

Roof Size (sq. ft.)	Roofing Squares	+10% Waste
1,000	10	11
1,500	15	16.5
2,000	20	22
2,500	25	27.5
3,000	30	33

Final Thoughts

Calculating roofing squares from square footage is simple once you know the formula.
Just divide your total roof area by 100 — and don’t forget to add 10–15% extra for waste.

If your roof has a slope, always apply the slope multiplier first to get accurate results. This ensures you buy the right amount of shingles, avoid shortages, and save time during installation.