Shingle Calculator
Enter the building size and pitch, or a roof area you already know. You get the bundles of shingles to buy, plus starter strip and ridge cap. Results update as you type.
Bundles of shingles
47 bundles
15.50 squares with 10% extra × 3 bundles
Buy 47 bundles of shingles, plus 2 starter and 2 ridge cap.
- Roof area1,409 sq ft (130.9 m²)
- Squares14.09
- Squares with extra15.50
- Starter strip bundles2 (151.1 ft, estimated)
- Ridge cap bundles2 (42.0 ft, estimated)
- At your price per bundleAdd a price
Field shingles come from the area and your extra. Starter (about 120 ft per bundle) and ridge cap (about 25 ft per bundle) come from the edge lengths; leave them blank to use a simple gable or hip estimate.
Planning estimate, not a quote. Disclaimer
How the shingle calculator works
It finds the roof area, converts it to squares, adds your extra for waste and multiplies by the bundles per square. Three bundles per square is right for most asphalt shingles, including 3-tab and architectural; some specialty products use more, so the calculator lets you choose 4 or 5. Starter strip and ridge cap are counted from the length of the eaves, rakes, ridge and hips.
Starter bundles = (eaves + rakes) ÷ 120.33 ft
Ridge cap bundles = (ridge + hips) ÷ 25 ft
Example: the default 40 × 28 ft house at 6/12 has 1,409 sq ft of roof. With 10% extra that is 15.5 squares and 47 bundles. The gable edges come to about 151 ft of starter (2 bundles) and 42 ft of ridge (2 bundles).
Where the numbers come from
GAF says most standard shingles, 3-tab and architectural, come three bundles to the square (33.3 sq ft per bundle). A bundle of GAF Pro-Start starter strip covers about 120.33 linear feet, and a bundle of Seal-A-Ridge cap covers 25 linear feet at a 6⅔-inch exposure. Your product may differ, so check the wrapper. More on the methodology page.
Edge lengths
Leave the starter and ridge fields empty and the calculator estimates a plain gable roof (ridge the length of the building, starter on the eaves and rakes) or a plain hip roof (ridge plus four hips, starter on the eaves only). Valleys, dormers and extra ridges add cap and starter; type your measured lengths to override the estimate.
Planning to see how many shingles are in each bundle? Read how many shingles are in a bundle or how many bundles make a square.
Frequently asked questions
How many bundles of shingles do I need?
Divide the roof area by 100 to get squares, add 10 to 15% for waste, then multiply by 3. The example roof of 1,409 sq ft needs 47 bundles.
How many bundles are in a square?
Three for most asphalt shingles. GAF notes some specialty shingles run four or five bundles per square.
How much waste should I add for shingles?
GAF suggests 10 to 15%. Hips, valleys, dormers and steep roofs push it toward the top of that range.
How many bundles of ridge cap do I need?
Divide the ridge and hip length by 25 ft and round up. 42 ft of ridge needs 2 bundles of Seal-A-Ridge-style cap.
Do I need starter strip?
Shingle makers call for a starter course at the eaves and rakes. A bundle of Pro-Start covers about 120.33 ft.
Related
Other roofing calculators
Sources
- GAF: How many bundles of shingles are in a square? (checked Nov 12, 2026)
- GAF: Pro-Start starter strip shingles (checked Nov 12, 2026)
- GAF Seal-A-Ridge listing (25 lineal ft per bundle, 45 pieces) (checked Nov 12, 2026)