Roofing & Exterior

Roof Pitch & Shingle Bundle Calculator

Determine your roof's true surface area from ground dimensions using standard slope multipliers, calculate exact shingle bundles and synthetic underlayment rolls, and estimate material costs.

Roofing "Squares" Required 15.5 Squares (1 Square = 100 sq ft)
Shingle Bundles to Order 47 bundles Standard 3 bundles per square
Total True Surface Area 1,417 sq ft Includes slope multiplier & eaves
Synthetic Underlayment 4 rolls Standard 4-square roll (400 sq ft)
Ridge Cap Shingles ~2 bundles For main ridge line & hips
Estimated Material Budget

Estimated Shingle & Dry-In Material Cost

Architectural Shingles (Materials Only) $1,786.00 Based on 47 bundles @ $38.00/bundle
Complete Dry-In Package (With Underlay & Nails) $2,286.00 Includes shingles + synthetic felt + coil roofing nails + drip edge
💡 Pro Roofing Tip: Always order at least 1 extra bundle of shingles beyond your exact count for starter strips along the eaves and rakes, plus ridge caps and future wind repairs.
📐 Technical Blueprint: Roof Pitch Geometry & Square Anatomy NRCA / IRC R905
Standard Pitch Slope Triangle Fixed Unit Run = 12 inches (Horizontal) Rise = 6" Rafter Slope (Pitch 6:12 = 1.118 Multiplier) Formula: Multiplier = √(1 + (Rise/12)²) 1 Roofing Square = 100 Sq Ft 10 ft × 10 ft Roof Deck Area (100 Sq Ft) Bundle 1 (~33.3 sq ft / ~70 lbs) Bundle 2 (~33.3 sq ft / ~70 lbs) Bundle 3 (~33.3 sq ft / ~70 lbs) Exactly 3 Bundles = 1 Cured Square Synthetic Felt Roll = 10 Squares (1,000 sq ft)
12" Unit Horizontal Run
Vertical Rise in Inches
Architectural Shingle Bundles (3/Square)
100 Sq Ft Structural Deck

Understanding Roof Squares, Pitch Multipliers, and Shingle Bundles

In the North American roofing trade, contractors never quote jobs in simple square feet. Everything is priced and ordered in Roofing Squares.

What Is a Roofing Square?

One roofing square equals exactly 100 square feet of roof surface. For example, a 2,000 sq ft roof is 20 squares.

How Shingle Bundles Work

Standard architectural asphalt shingles (such as GAF Timberline HDZ, Owens Corning Duration, or CertainTeed Landmark) are packaged so that 3 bundles cover exactly 1 roofing square. Due to weight limits for delivery drivers and rooftop safety, each bundle weighs roughly 65 to 80 pounds.

Slope Multiplier Reference Table

Pitch (Rise/Run) Angle (Degrees) Slope Factor Multiplier Walkability
3/1214.0°1.031Easy walk
4/1218.4°1.054Standard walk
6/1226.6°1.118Moderate / Cougar paws recommended
8/1233.7°1.202Steep / Roof jacks & harnesses needed
10/1239.8°1.302Very steep
12/1245.0°1.414Extreme pitch