Free estimate — verify against local code before building
Roofing Materials / Shingle Calculator
Convert roof dimensions and pitch into a purchase-ready shingle takeoff.
What this calculator includes
Turn a measured roof footprint, pitch, and overhang into the shingle bundles, underlayment rolls, and roofing nails to order. Product coverage and prices stay editable so the takeoff matches the packages available to you.
How to use this roofing materials calculator
- 01
Measure the plan
Enter the building length and width at the wall line, then add the horizontal overhang at each edge.
- 02
Apply roof pitch
Choose the rise in inches for every 12 inches of run. The calculator multiplies horizontal plan area by √(12² + rise²) ÷ 12.
- 03
Match the package
Use installed coverage from the exact shingle bundle and underlayment roll, not package dimensions or marketing area.
- 04
Review waste and order
Set waste for valleys, hips, dormers, starter cuts, and layout, then confirm the rounded order with the roofing plan and supplier.
Worked example
Example: 40 × 28 ft gable roof at 6-in-12
With 1-foot overhangs, the plan is 42 × 30 = 1,260 sq ft. A 6-in-12 multiplier of 1.118 produces about 1,409 sq ft of roof. Adding 10% waste gives about 1,550 sq ft to cover, then bundle, roll, and nail quantities round up to whole packages.
Practical buying and overage guidance
Buy from one shingle production lot when possible, verify color and bundle coverage, and confirm compatible starter, ridge cap, underlayment, flashing, ventilation, fasteners, and ice-barrier details before delivery.
Continue the project
Upgrade Roof Drainage
Plan roof area, gutter runs, downspouts, fittings, extensions, drainage stone, grading, excavation, supplies, and contractor pricing.
Open the project workflow →Calculation sources and review
Primary references and formula assumptions are linked so you can verify them against the selected product, supplier, and adopted local requirements.
Internal formula review completed July 13, 2026. What this review covers
- Asphalt Roofing Manufacturers Association — residential roofing (opens in a new tab)
Industry guidance for asphalt roofing products and installation variables.
- GAF — roofing document library (opens in a new tab)
Manufacturer documents for installed coverage, slope limits, and accessory requirements.
- OSHA — residential construction fall protection (opens in a new tab)
Roof work presents serious fall hazards and requires appropriate protection.
Frequently asked questions
How many bundles of shingles make one roofing square?
Many laminated asphalt shingles use three bundles per 100-square-foot roofing square, but some products use more. Enter the square-foot coverage printed for the exact bundle instead of assuming three.
What is the roof pitch multiplier?
It converts horizontal plan area to sloped surface area. For a 6-in-12 pitch, the multiplier is √(12² + 6²) ÷ 12, or about 1.118.
How much shingle waste should I add?
Simple gable roofs often need less waste than roofs with hips, valleys, dormers, or short courses. Use the roof plan and the shingle maker's layout instructions; 10% is a planning starting point, not a universal rule.
Does the shingle count include ridge cap and starter shingles?
No. This result covers field shingles. Confirm whether dedicated starter and hip/ridge products are required and measure those linear runs separately.
Why is underlayment coverage editable?
Roll size is not always installed coverage. Laps, double coverage at low slopes, and local or manufacturer requirements can reduce effective coverage.