Roofing Calculator
Calculate squares of shingles and materials needed based on roof footprint and pitch
Measurement Method
Roof Pitch
Pitch factor: 1.054× — a 4:12 pitch adds 5% more surface area than the footprint.
Shingle Type & Waste
Enter your roof dimensions to calculate materials
Tips & Notes
- •1 roofing square = 100 sq ft. Most shingles are sold 3 bundles per square.
- •Add 10% waste for a simple gable roof; 15–20% for hips, valleys, or dormers.
- •Architectural (dimensional) shingles last 25–30 years vs. 15–20 for 3-tab.
- •Check local building codes — most require ice and water shield at eaves in cold climates.
- •Never roof over more than 2 layers of shingles — strip to deck for best results.
Recommended Products
Popular items for this project — links may earn a commission.
Materials & Supplies
Pro tips for roofing
- ›1 roofing square = 100 sq ft. Most shingles are sold 3 bundles per square.
- ›Add 10% waste for a simple gable roof; 15–20% for hips, valleys, or dormers.
- ›Architectural (dimensional) shingles last 25–30 years vs. 15–20 for 3-tab.
- ›Check local building codes — most require ice and water shield at eaves in cold climates.
- ›Never roof over more than 2 layers of shingles — strip to deck for best results.
Frequently asked questions
How many bundles of shingles do I need?▾
Most architectural shingles are sold 3 bundles per square (100 sq ft of coverage). A 2,000 sq ft roof needs 20 squares × 3 = 60 bundles plus 10% waste = 66 bundles. For complex roofs with hips and valleys, add 15%.
What is a 'square' in roofing?▾
A roofing square equals 100 square feet of roof area. It's the standard unit for ordering shingles, underlayment, and pricing. A 2,400 sq ft roof equals 24 squares. Pricing is usually quoted per square.
How do I measure roof pitch?▾
Roof pitch is rise over 12 inches of run. A 6/12 pitch means the roof rises 6 inches for every 12 inches horizontal. Most residential roofs are 4/12 to 9/12. Steeper roofs need more shingles per square foot of footprint — the calculator adjusts for this.
How much does a new roof cost in 2026?▾
Asphalt 3-tab shingles: $4–$6/sq ft installed ($8,000–$12,000 for a 2,000 sq ft roof). Architectural shingles: $5–$8/sq ft. Metal: $8–$15/sq ft. Tile: $10–$20/sq ft. Tear-off, decking repair, and underlayment add $1–$3/sq ft.
Can I roof over existing shingles?▾
Some codes allow one overlay (a second layer of shingles on top), but it's not recommended — it traps heat, voids many warranties, and hides decking problems. Always tear off and inspect the decking before reroofing. Two layers maximum, ever.