Roofing Calculator

Calculate how much roofing material you need for any roof type and pitch. Supports asphalt shingles, metal, tile, and slate roofing. Get results in roofing squares, bundles needed, and cost estimates. Automatically accounts for roof pitch and includes customizable waste factor.

Roofing Calculator: Calculate roofing materials needed for your project. Accounts for roof pitch, type, and waste factor. Results in roofing squares (100 sq ft each).

Building Dimensions

Roof Pitch (Rise/Run)

Common: 4-12 (low) to 12-12 (steep)

Standard run is 12 inches

Current pitch: 6/12 (26.6°)

Material Settings

Standard 3-tab: 3 bundles/square

Typical: 10-15% for cuts and waste

1 roofing square = 100 sq ft

How It Works

1. Select Roof Type & Material

Choose your roof type (Gable, Hip, Shed, or Flat) and roofing material (Asphalt Shingles, Metal, Tile, or Slate). Different types require different amounts of material.

2. Enter Building Dimensions

Input the length and width of your building in feet or meters. This is the footprint area, not the actual roof area.

3. Set Roof Pitch

Enter the roof pitch as rise over run (e.g., 6/12 means 6 inches of rise for every 12 inches of run). Common pitches range from 4/12 (low slope) to 12/12 (steep).

4. Get Results & Estimate

See total roof area, roofing squares needed (1 square = 100 sq ft), bundles for shingles, and optional cost estimate. Results include waste factor.

Examples

Example 1: Gable Roof (Standard House)

Roof Type: Gable Material: Asphalt Shingles Building: 40' × 30' Pitch: 6/12 (26.6°) Bundles Per Square: 3 Waste Factor: 10% Results: Total Roof Area: 1,342 sq ft (124.7 m²) With Waste: 1,476 sq ft (137.1 m²) Roofing Squares: 15 squares Bundles Needed: 45 bundles A typical 1,200 sq ft house with gable roof. The 6/12 pitch increases roof area by about 12% compared to flat.

Example 2: Hip Roof (Ranch House)

Roof Type: Hip Material: Asphalt Shingles Building: 50' × 40' Pitch: 4/12 (18.4°) Bundles Per Square: 3 Waste Factor: 15% Price: $95/square Results: Total Roof Area: 2,295 sq ft (213.2 m²) With Waste: 2,639 sq ft (245.2 m²) Roofing Squares: 27 squares Bundles Needed: 81 bundles Estimated Cost: $2,565 Hip roofs use 15% more material than gable roofs due to four sloped sides. 15% waste for complex cuts at hips.

Example 3: Shed Roof (Small Building)

Roof Type: Shed Material: Metal Roofing Building: 20' × 12' Pitch: 3/12 (14.0°) Waste Factor: 10% Price: $150/square Results: Total Roof Area: 246 sq ft (22.9 m²) With Waste: 271 sq ft (25.2 m²) Roofing Squares: 3 squares Estimated Cost: $450 Small shed or workshop with single-slope roof. Metal roofing is durable and low-maintenance for outbuildings.

Frequently Asked Questions

What is a roofing square?

A roofing square is a unit of measurement equal to 100 square feet of roof area. Roofing materials are typically sold by the square. For example, if your roof is 2,400 square feet, you need 24 squares of roofing material. This standardized measurement makes it easier to estimate materials and costs across different roof sizes.

How do I measure roof pitch?

Roof pitch is expressed as rise over run (e.g., 6/12). The rise is the vertical height in inches, and the run is always 12 inches horizontal. To measure: place a level horizontally on the roof, measure up 12 inches from the level, then measure the vertical distance from the level to the roof. Common pitches: 4/12 (low), 6/12 (standard), 8/12 (steep), 12/12 (very steep, 45°).

How many bundles of shingles do I need?

Standard 3-tab asphalt shingles come in bundles, with 3 bundles covering 1 roofing square (100 sq ft). Architectural or dimensional shingles often require 4 bundles per square. Calculate total squares needed, multiply by bundles per square, then add 10-15% for waste. For example, a 15-square roof needs 45 bundles of 3-tab shingles (15 × 3), plus 5-7 extra bundles for waste.

What waste factor should I use for roofing?

Use 10% waste factor for simple gable or shed roofs with minimal cuts. Use 15% for hip roofs, complex roof shapes, or roofs with many valleys, dormers, and skylights. Use 20% for very complex roofs with multiple angles and features. The waste accounts for cuts around chimneys, vents, edges, starter courses, and mistakes. Always round up - running short mid-project is costly.

How long do different roofing materials last?

Asphalt shingles: 15-30 years (3-tab: 15-20 years, architectural: 25-30 years). Metal roofing: 40-70 years. Tile (clay/concrete): 50-100+ years. Slate: 75-200 years. Wood shakes: 25-30 years. Lifespan depends on climate, installation quality, maintenance, and material grade. Hot, sunny climates reduce asphalt shingle life. Proper attic ventilation extends all roofing lifespans.