Roofing Shingle Calculator

Estimate roof area, roofing squares, shingle bundles, underlayment, starter shingles, ridge caps, waste allowance, and material cost.

Roof Measurement

Measurement Method

Building Length (ft)

Building Width (ft)

Roof Overhang on Each Side (in)

Roof Pitch

Enter the outside building dimensions. The calculator adds the overhang to all four sides and applies the selected roof-pitch multiplier.

Shingles & Waste

Waste Allowance (%)

Shingle Bundles Per Square

One roofing square equals 100 square feet. Many asphalt shingles use three bundles per square, but product coverage varies. Check the package before purchasing.

Accessory Materials

Underlayment Coverage Per Roll (sq ft)

Roof Edge Receiving Starter Shingles (linear ft)

Starter Coverage Per Bundle (linear ft)

Ridge and Hip Length (linear ft)

Ridge Cap Coverage Per Bundle (linear ft)

Starter shingles may be installed along eaves and sometimes rakes. Ridge-cap coverage varies by product and exposure.

Optional Material Prices

Price Per Shingle Bundle ($)

Price Per Underlayment Roll ($)

Price Per Starter Bundle ($)

Price Per Ridge-Cap Bundle ($)

Additional Material Costs ($)

Additional materials may include nails, flashing, drip edge, ice-and-water membrane, vents, sealant, delivery, and disposal.

Roofing Estimate

Horizontal Roof Footprint —

Roof Pitch Multiplier —

Calculated Roof Surface Area —

Roofing Squares Before Waste —

Waste Allowance —

Roofing Squares With Waste —

Shingle Bundles —

Underlayment Rolls —

Starter Bundles —

Ridge-Cap Bundles —

Estimated Material Cost —

This calculator provides a planning estimate. Valleys, dormers, hips, intersecting roofs, damaged decking, unusual layouts, product exposure, local code requirements, and installation methods may change actual material quantities.

What Is a Roofing Square?

Roofing materials are commonly measured in squares. One roofing square covers 100 square feet of roof surface. A 2,000-square-foot roof therefore contains 20 roofing squares before waste.

Roofing Squares = Roof Surface Area ÷ 100

How Roof Pitch Changes Surface Area

Roof pitch describes vertical rise for every 12 inches of horizontal run. A steeper roof has more surface area than its horizontal footprint. The calculator applies a slope multiplier based on the selected pitch.

How Many Bundles Are in a Roofing Square?

Many common asphalt shingles require approximately three bundles per roofing square. Heavier, larger, or specialty shingles may use a different number. Always use the coverage printed on the selected product.

How Much Roofing Waste Should You Add?

Ten percent is a common starting allowance for a simple gable roof. Hips, valleys, dormers, complex intersections, starter courses, damaged shingles, and inexperienced cutting may require a larger allowance.

Starter Shingles and Ridge Caps

Starter shingles protect roof edges and provide the correct seal for the first shingle course. Ridge and hip caps cover roof peaks and hips. These products are estimated separately because they are measured by linear coverage rather than roof area.

Other Roofing Materials to Plan For

For a separate framing-layout estimate, estimate common-rafter geometry; the shingle calculation does not specify structural framing. If sheathing is separately specified, plan roof-sheathing cuts and sheet purchases from the required panel dimensions and cut list. This does not establish panel span rating or a structural design. For a separate collection plan, estimate roof rainwater collection using the appropriate horizontal catchment area, not the sloped roofing material area.

A complete roofing project may also require ice-and-water membrane, drip edge, flashing, ventilation, roofing nails, sealant, replacement decking, disposal, permits, and fall protection. Confirm local requirements and manufacturer instructions before purchasing or installing materials.