Roofing Shingle Material Calculator

Calculate the number of shingle squares, bundles, nails, and ridge cap bundles needed for your roofing project based on roof dimensions and pitch.

Roof Length (ft)

Roof Width / Rafter Run (ft) (horizontal distance from eave to ridge)

Roof Pitch (rise per 12 in run, e.g. 6 for 6:12)

Number of Roof Sides / Planes

Waste Factor (%)

Ridge Length (ft) (total length of all ridges and hips)

1. Slope Factor
Slope Factor = √(pitch² + 12²) / 12
Converts horizontal (plan) area to actual sloped surface area.

2. Gross Roof Area
Area = Length × (Width × Slope Factor) × Number of Sides

3. Adjusted Area
Adjusted Area = Gross Area × (1 + Waste% / 100)

4. Squares
Squares = Adjusted Area / 100 (1 square = 100 sq ft)

5. Bundles
Bundles = ⌈Squares × 3⌉ (standard 3-tab: 3 bundles/square)

6. Nails
Nails = ⌈Squares × 320⌉ (4 nails × ~80 shingles/square)
Nail Boxes = ⌈Nails / 300⌉ (~300 nails per 1-lb box of 1¾" roofing nails)

7. Ridge Cap Bundles
Ridge Bundles = ⌈Ridge Length / 35⌉ (1 bundle covers ~35 linear ft)

8. Underlayment
Rolls = ⌈Squares / 4⌉ (1 roll of 15-lb felt covers ~400 sq ft)

Standard 3-tab asphalt shingles are assumed (3 bundles per square). Architectural/dimensional shingles may require 4 bundles per square — verify with your supplier.
1 roofing square = 100 sq ft of roof surface area (industry standard).
Slope factor formula is derived from the Pythagorean theorem applied to the roof pitch triangle (rise:run = pitch:12).
A 10% waste factor is recommended for simple gable roofs; use 15–20% for complex roofs with hips, valleys, and dormers.
Nail count assumes 4 nails per shingle and approximately 80 shingles per square (standard 3-tab, 12"×36" shingles).
Nail box estimate based on 1¾" (1.75") galvanized roofing nails at ~300 nails per pound.
Ridge cap coverage of 35 linear ft per bundle is a common industry estimate; verify with manufacturer specs.
Underlayment estimate based on standard 15-lb roofing felt (4-square roll). Synthetic underlayment rolls vary — check product specs.
This calculator does not account for starter strips, drip edge, flashing, or ice-and-water shield — consult a roofing professional for a complete material list.
References: NRCA (National Roofing Contractors Association) guidelines; IRC (International Residential Code) roofing provisions.

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