Exterior Paint Calculator
Repaint the siding while the roof crew is up there.
Roofing
How many bundles of roof shingles do I need?
Enter the roof footprint (house length × width under the roof) and the pitch, and the shingle calculator returns the true roof area in squares plus shingle bundles. A 30 × 50 ft footprint at a 6/12 pitch covers about 1,677 sq ft ≈ 17 squares — needing roughly 56 bundles of 3-tab shingles with 10% waste.
Roofing material is sold by the "square" (100 sq ft) and shingles by the bundle, so this estimator starts from the house footprint you can measure on the ground: multiply by the pitch factor for your roof's rise in 12, convert to squares, then apply waste (10% for a simple gable, more for valleys and dormers) to reach the bundle count to order for your re-roof project.
Frequently asked questions
How many bundles of shingles are in a square?
Three bundles of 3-tab shingles cover one square (100 sq ft). Architectural (dimensional) shingles are thicker, so most brands need 4 bundles per square — always verify on the bundle wrapper.
How do I estimate shingles for my house?
Measure the roof footprint (length × width), multiply by the pitch factor, divide by 100 for squares, then multiply by bundles per square plus 10% waste. A 1,500 sq ft footprint at 6/12 works out to about 56 bundles of 3-tab shingles.
How much waste should I add when buying shingles?
Add 10% for cutting, valleys, hips and mistakes — more on complex roofs with many valleys and penetrations. Order an extra bundle or two of the same dye lot so touch-ups match later.
Do I need separate material for hips and ridges?
Yes. Cap/ridge shingles are sold separately and one bundle covers about 30–35 linear feet of hip and ridge. Add starter shingles along the eaves plus valley lining if your code and manufacturer require them.
How do I measure the roof pitch for the calculator?
Pitch is rise over run, usually written in inches per 12 (e.g. 6/12). The calculator applies the matching pitch factor — about 1.05 for 4/12, 1.12 for 6/12, 1.20 for 8/12 and 1.41 for a 12/12 — to turn your measured footprint into the true sloped roof area.
Do shingles from different batches match in color?
Usually close, but even the same model can differ slightly between dye lots, which is visible across a large roof. Order everything at once and store a spare bundle or two from that same lot for future repairs.
Shingles Calculator
Imperial
ft
Longest horizontal run under the roof.
ft
Roughly the house width for a gable roof.
Waste allowance
Enter your roof footprint to see the result.
–
squares
Does not include hip, ridge, starter or valley pieces — add them when ordering.
How it works
How to use this shingle calculator
1Measure the footprint
Roof area grows with pitch, so start from the flat footprint: the house length × width covered by the roof. For a gable roof that's about the house's footprint; for complex rooflines, split into rectangles.
- Add overhangs: include 1–2 ft of eave overhang in each direction.
- Multi-story homes: the footprint is still the roof's horizontal extent.
- Garage and porch roofs: add their footprints too.
2Estimate the pitch
Pitch is rise ÷ run, written like "6/12" (6 inches up per 12 inches across). Steeper roofs have more surface area than their footprint suggests.
- If unsure, check from the attic or measure with a level and tape.
- 4/12: gentle; 6/12: typical; 8/12+: steep.
- The pitch factor table below lists the multipliers.
3From squares to bundles
Roofing is sold by the "square" — 100 sq ft of finished shingles. A square of 3-tab shingles takes 3 bundles; architectural shingles are heavier and take 4 bundles per square. Add 10% for cutting, valleys and mistakes.
The math
Shingle quantity formula
True roof area = footprint × pitch factor • Squares = roof area ÷ 100
Bundles = squares × bundles per square × (1 + waste)
Worked example — 50 × 30 ft footprint = 1,500 sq ft; 6/12 pitch (×1.118); 3-tab (3/sq), 10% waste:
1,500 × 1.118 = 1,677 sq ft = 16.8 squares; 16.8 × 3 × 1.1 = 55.4 → 56 bundles.
1,500 × 1.118 = 1,677 sq ft = 16.8 squares; 16.8 × 3 × 1.1 = 55.4 → 56 bundles.
Pitch table
Roof pitch and area multiplier
| Pitch | Angle | Area factor |
|---|---|---|
| 4/12 | 18° | 1.05× |
| 6/12 | 27° | 1.12× |
| 8/12 | 34° | 1.20× |
| 10/12 | 40° | 1.30× |
| 12/12 | 45° | 1.41× |
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