Roofing & Gutters
Roof Square Footage Calculator
Enter the house length and width from the ground, how far the roof overhangs each wall, and the pitch. You get the footprint with overhangs, the slope factor, the roof surface in square feet and the number of roofing squares.
Worked example
- Footprint with overhangs = (40 + 2) x (28 + 2) = 1,260 sq ft.
- Slope factor for 6/12 = 1.118; roof area = 1,260 x 1.118 = 1,409 sq ft.
- One roofing square is 100 sq ft: 14.09 squares.
Common sizes at a glance
| Size | Roof area | Roofing squares |
|---|---|---|
| 30 x 24 ft house, 4/12 | 877 sq ft | 8.77 |
| 40 x 28 ft house, 6/12 | 1,409 sq ft | 14.09 |
| 50 x 30 ft house, 6/12 | 1,860 sq ft | 18.60 |
| 60 x 32 ft house, 8/12 | 2,534 sq ft | 25.34 |
| 40 x 40 ft house, 5/12 | 1,911 sq ft | 19.11 |
Measure the walls, then add the eaves
You do not need to go up on the roof. Measure the outside of the house walls with a long tape, then estimate how far the eaves stick out past the walls. The calculator adds the overhang to both ends of each dimension.
In the example, a 40 x 28 ft house with a 1 ft overhang becomes a 42 x 30 ft footprint, or 1,260 sq ft. Ignore attached porches with their own roof and measure them separately.
From footprint to roof surface
The roof is tilted, so its surface is larger than the footprint. The slope factor converts one to the other. At 6 in 12 the factor is 1.118, which turns 1,260 sq ft into 1,409 sq ft of roof.
Not sure of the pitch? The roof pitch calculator shows how to find it from the attic or a gable end.
Why roofers talk in squares
A roofing square is 100 sq ft of roof surface. Shingles, underlayment and labor are often priced per square, so 14.09 squares is the figure a supplier or crew will ask for.
The square count here is the bare surface, with no waste. Add waste when you turn squares into bundles, which the shingle calculator does along with starter and ridge cap.
Where this shortcut works and where it misses
The method holds for simple gable and hip roofs where every plane has the same pitch, because each plane tilts by the same factor. It gets less accurate as the roof gets more complex.
- Dormers add wall and roof area the footprint does not show
- Mixed pitches: run each section on its own and add them
- Valleys and many hips raise waste, not area
- Low-slope sections may need a different product
Questions
How many squares is a 2,000 sq ft house roof?
It depends on the footprint and pitch, not the living area. A two-story house has a much smaller footprint than a ranch with the same floor area. The table shows a 50 x 30 ft house at 6/12 is 18.60 squares.
Does a hip roof have more area than a gable roof?
At the same pitch and overhang, the surface area is about the same, since both are the footprint times the slope factor. Hips add ridge and waste, not area.
Should I include the garage?
Yes, if it shares the roof. Measure it as its own rectangle if it has a different pitch.
How this works: formulas and typical values are listed on our method page; every data source and its license is on sources.
Last reviewed November 2026.