Free tool
Roofing squares calculator
Enter the roof's footprint and pitch, or the planes measured on the roof, and a waste allowance. You get roofing squares, shingle bundles, starter, ridge cap and underlayment rolls. Coverage defaults come from GAF product data; change them to match your shingle.
Roofing needed
24.6 squares2,236 sq ft of roof plus 10% waste
- Squares before waste
- 22.36
- Slope multiplier
- 1.118
- Shingle bundles
- 74
- Starter bundles
- 2
- Ridge cap bundles
- 2
- Underlayment rolls
- 3
Bundles rounded up. Underlayment from roof area without waste; add rolls for extra laps. Ice and water shield and drip edge not included.
24.6 squares including 10% waste (2,236 sq ft of roof): 74 shingle bundles, 2 starter bundles, 2 ridge cap bundles and 3 underlayment rolls.
How it's calculated
- Slope multiplier = √(1 + (rise ÷ 12)²)
- Roof area = footprint area × slope multiplier (or the sum of planes measured on the slope)
- Squares = roof area ÷ 100; with waste = squares × (1 + waste %)
- Shingle bundles = squares with waste × bundles per square, rounded up
- Starter bundles = (eaves + rakes) ÷ lin ft per bundle; ridge cap bundles = (ridges + hips) ÷ lin ft per bundle
- Underlayment rolls = roof area ÷ roll coverage, rounded up
How to use it
- 1Measure the roof. Enter the footprint area including overhangs and the pitch, or measure each plane on the roof surface.
- 2Set waste. Use about 10% for a simple gable and more for hips, valleys and dormers.
- 3Check coverage. Most architectural and 3-tab shingles are 3 bundles per square, but some are 4 or 5. Check the bundle wrapper.
- 4Add edges. Enter eaves plus rakes for starter, and ridges plus hips for ridge cap.
- 5Order. Read bundles, starter, ridge cap and underlayment rolls as your material order.
Worked example
A 2,000 sq ft footprint at 6/12 pitch, 10% waste, 3 bundles per square, 240 ft of eaves and rakes and 40 ft of ridge.
- Multiplier = √(1 + 0.5²) = 1.118
- Roof area = 2,000 × 1.118 = 2,236 sq ft = 22.36 squares
- With waste = 22.36 × 1.10 = 24.6 squares
- Bundles = 24.6 × 3 = 73.8 → 74 bundles
- Starter = 240 ÷ 120 = 2 bundles; ridge cap = 40 ÷ 25 = 1.6 → 2 bundles
- Underlayment = 2,236 ÷ 1,000 = 2.24 → 3 rolls
Order 74 bundles of shingles, 2 bundles of starter, 2 bundles of ridge cap and 3 rolls of synthetic underlayment.
Sources
- GAF, Timberline HD Shingles technical data sheet (hosted by the Roofing Contractors Association of BC). Accessed 2026-11-03.
Bundles per square: 3. Pieces per square: 64. Exposure 5⅝ in. Recommended starter: ProStart or WeatherBlocker; hip and ridge: Timbertex, Seal-A-Ridge and others.
- GAF, Pro-Start Eave/Rake Starter Strip Shingles sell sheet. Accessed 2026-11-03.
Coverage approximately 120.33 lineal feet per bundle. The calculator defaults to 120.
- GAF, Seal-A-Ridge Ridge Cap Shingles sell sheet (RESHR112, 2023). Accessed 2026-11-03.
4 bundles cover approximately 100 linear feet, or about 25 linear feet per bundle.
- GAF, FeltBuster High-Traction Synthetic Roofing Felt sell sheet. Accessed 2026-11-03.
Roll size 10 squares (1,000 sq ft), excluding laps; 48 in. × 250 ft. Lower the coverage if you lap more than the instructions call for, or use a felt with smaller rolls.
- Vertigraph (takeoff and estimating software), How to calculate roofing squares. Accessed 2026-11-03.
Slope multiplier = √(1 + (rise ÷ 12)²), e.g. 1.118 at 6/12. Waste: about 10% for a simple gable, 12–15% for a hip roof, 15–20% for hips and valleys with dormers, 18–22% for heavily cut roofs.
- Fine Homebuilding, Don't Fall Short on Shingles: How to Estimate Materials for Roofing Projects (Mike Guertin). Accessed 2026-11-03.
Three bundles to a square is most common, but heavier 3-tab and laminated shingles can take four or five. Waste rises with every hip, valley and obstruction.
FAQ
Roofing calculator questions
Have a question we didn't cover? Book a demo and ask a product specialist.
What is a roofing square?
100 square feet of roof surface. A 2,236 sq ft roof is 22.36 squares before waste.
How many bundles of shingles are in a square?
Most architectural and 3-tab shingles, including GAF Timberline, are 3 bundles per square. Some heavier or designer shingles are 4 or 5, so check the wrapper and change the setting.
How much waste should I add for a roof?
Estimating guides use about 10% for a simple gable, 12–15% for a hip roof and 15–20% or more for roofs with valleys, dormers and other cuts. Measured takeoffs from a report can justify less.
Why does pitch matter?
A sloped roof has more surface than its footprint. At 6/12 the roof is about 11.8% bigger than the area it covers; at 12/12 it's 41.4% bigger.
Does this include ice and water shield or drip edge?
No. Measure eaves, valleys and penetrations for ice and water shield and the perimeter for drip edge, and add them to your order separately.
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