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How Many Squares Is My Roof?
A roofing "square" is simply 100 square feet of roof. Getting your square count right is the foundation of every shingle, underlayment, and cost estimate — and you can do it from the ground.
What a square means
One square = 100 sq ft of roof surface. A 24-square roof means 2,400 sq ft of surface to cover. Shingles are wrapped and sold around this unit (3 bundles per square), and contractors quote by the square, so it is the number you want.
Step 1: Measure the footprint
From the ground, measure the length and width of the house including the roof overhangs, not just the walls. Multiply them for the footprint area. Break complex shapes (L-shapes, wings) into rectangles and add them up.
Step 2: Multiply by the pitch multiplier
Because the roof is sloped, its surface is larger than the footprint. Multiply by the pitch multiplier:
| Pitch | Multiplier |
|---|---|
| 3/12 | 1.031 |
| 4/12 | 1.054 |
| 6/12 | 1.118 |
| 8/12 | 1.202 |
| 10/12 | 1.302 |
| 12/12 | 1.414 |
Not sure of your pitch? See Roof Pitch to Angle, or measure it with the Roof Pitch Calculator.
Step 3: Divide by 100
Worked example
A 40 ft × 30 ft footprint (with overhangs) on a 6/12 roof:
- Footprint: 40 × 30 = 1,200 sq ft
- Roof area: 1,200 × 1.118 = 1,342 sq ft
- Squares: 1,342 ÷ 100 = ~13.4 squares
Turn squares into materials
Once you have squares, the shingle and underlayment math is quick — or let the tool do it:
For the full walk-through, see How Many Bundles of Shingles Do I Need?
Frequently asked questions
What is a roofing square?
100 square feet of roof surface — the standard unit for estimating and selling roofing.
How many squares is a 2,000 sq ft roof?
If that's the true sloped area, 20 squares. If it's the footprint, apply the pitch multiplier first (a 6/12 roof ≈ 22.4 squares).
Do I include overhangs?
Yes — measure to the edge of the eaves and rakes, not the walls.