10 Minute BidsRoof squares calculatorSquares and bundles from a footprint.
Enter the house's footprint, overhang and pitch. You get the roof area, squares and shingle bundles, with waste for the roof's shape. Every step of the math is shown.
Your estimate
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| Area under the rooffootprint plus overhang, measured level | — |
|---|---|
| Pitch factor√(1 + (rise ÷ 12)²) | — |
| Roof areaon the slope, before waste | — |
| Waste | — |
| Roof area with waste | — |
| Squares100 sq ft each | — |
| Bundles3 a square, rounded up | — |
How we got it
Skip the math — upload your plans. We measure it all on a 3D model of your house.
Priced per plan setShingle roofing bid, 3D model included
Upload your plansWhere hand math goes wrong: dormers, valleys and roofs with planes at different pitches. This calculator uses one pitch for the whole roof, and the waste % stands in for the cuts. On a cut-up roof, measure each plane, or upload your plans and we measure every plane on a 3D model.
This is an estimate from the numbers you enter. It doesn't see the roof as it really is: rotten decking, old layers under a re-roof, or crickets and saddles. Starter strip, ridge cap and underlayment are extra. Confirm measurements on site before you order materials or sign a contract.
The roof squares formula.
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Find the area under the roof
Add the overhang all around the footprint, measured level.
(length + 2 × overhang) × (width + 2 × overhang)any footprint with square corners: area + perimeter × overhang + 4 × overhang² -
Multiply by the pitch factor
The pitch factor is how much longer the roof is on the slope than across it level. When every plane has the same pitch, hips and valleys don't change the total.
pitch factor = √(1 + (rise ÷ 12)²) -
Add waste
For the cut-offs at rakes, hips and valleys. Typical: 10% for a simple gable, 15% for a hip, 20% for a cut-up roof.
with waste = roof area × (1 + waste %) -
Count squares and bundles
A square is 100 sq ft of roof. Most shingles come 3 bundles to a square; round the bundles up.
squares = area ÷ 100 · bundles = squares × 3, rounded up
Worked exampleA 40 × 30 ft house with a 12 in overhang and a 6/12 pitch is 42 × 32 = 1,344 sq ft under the roof. × 1.1180 = 1,502.6 sq ft of roof, + 10% = 1,652.9 sq ft: 16.53 squares, and 16.53 × 3 = 49.59, so 50 bundles.
| Pitch | Factor | Roof over 1,000 sq ft |
|---|---|---|
| 1/12 | 1.0035 | 1,003 sq ft |
| 2/12 | 1.0138 | 1,014 sq ft |
| 3/12 | 1.0308 | 1,031 sq ft |
| 4/12 | 1.0541 | 1,054 sq ft |
| 5/12 | 1.0833 | 1,083 sq ft |
| 6/12 | 1.1180 | 1,118 sq ft |
| 7/12 | 1.1577 | 1,158 sq ft |
| 8/12 | 1.2019 | 1,202 sq ft |
| 9/12 | 1.2500 | 1,250 sq ft |
| 10/12 | 1.3017 | 1,302 sq ft |
| 11/12 | 1.3566 | 1,357 sq ft |
| 12/12 | 1.4142 | 1,414 sq ft |
| 14/12 | 1.5366 | 1,537 sq ft |
| 16/12 | 1.6667 | 1,667 sq ft |
| 18/12 | 1.8028 | 1,803 sq ft |
The calculator carries every digit and rounds only what it shows.
Skip the math —upload your plans.
We build your roof in 3D from your plan set and measure every plane at its own pitch, valleys and dormers as drawn. Your shingle bid lists squares with waste, starter, ridge cap and flashing. You spend about 10 minutes checking it against your plans.
Priced per plan setShingle roofing bid, 3D model included
Or see what’s in a shingle roofing bid.
Roof squares questions.
How many square feet are in a roofing square?
A roofing square is 100 square feet of roof surface. A roof of 2,000 square feet is 20 squares.
How do I find the roof area from the footprint?
Add the overhang to the footprint to get the area under the roof, measured level. Multiply it by the pitch factor, the square root of 1 + (rise ÷ 12)². A 6/12 roof has a factor of 1.118, so 1,500 square feet under the roof is about 1,677 square feet of roof.
How many bundles of shingles are in a square?
Most three-tab and architectural shingles come 3 bundles to a square, so one bundle covers about 33.3 square feet. Check the wrapper: some heavy designer shingles take 4 or 5 bundles a square. Starter strip and ridge cap are extra.
How much waste should I add for a roof?
Typical starting points are 10% for a simple gable roof, 15% for a hip roof and 20% for a cut-up roof with valleys and dormers. The roof's real shape sets the real number.
Does the pitch factor work on a hip roof?
Yes, when every plane has the same pitch: hips and valleys move the edges, not the total area. Planes at different pitches, dormers and valleys are where hand math goes wrong, so measure each plane, or upload your plans and we measure every plane on a 3D model.