Roof Shingle Calculator
Work out how many shingle bundles a roof needs — from the footprint, pitch and your manufacturer's bundle coverage.
Shingles are sold by the bundle, but the roof is measured in squares — and the link is the bundle coverage printed on the packaging. This calculator uses your manufacturer's figure, never a guess.
For the whole roofing job (squares and underlayment), use the roofing calculator.
Your results
Enter your measurements and press Calculate.
Quantities are rounded up to whole tiles, planks, boxes or bags, after the wastage allowance. Cost appears only when you enter a price.
Formula
All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.
How to use this calculator
- Measure the roof footprint (length × width).
- Enter the pitch — rise per 12 in of run.
- Enter the bundle coverage from the manufacturer (usually 33.3 ft²).
- Set wastage at 10–15% and add a price per bundle for a cost estimate.
Worked example
| Footprint | 30 ft × 40 ft = 1,200 ft² |
|---|---|
| Pitch | 6/12 → slope factor 1.118 |
| Roof area | 1,200 × 1.118 = 1,341.64 ft² = 13.42 squares |
| Bundles (33.3 ft² each, 10% wastage) | ⌈(1,341.64 × 1.10) ÷ 33.3⌉ = 45 bundles |
Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.
Frequently asked questions
How many bundles of shingles do I need?
Divide the roof area (with wastage) by the bundle coverage. A 30 × 40 ft roof at 6/12 pitch needs 45 bundles of 33.3 ft². Enter your manufacturer's coverage above — it varies by shingle type.
How many bundles are in a square?
Three bundles of standard 3-tab shingles make one square (100 ft²). Architectural shingles can differ — check the packaging, which states the coverage per bundle.
Do I need extra shingles for the ridge?
Yes — ridge cap shingles are separate. A bundle of ridge caps covers about 20–30 linear feet of ridge. Measure the ridge length and add it to your order.
What wastage should I allow for shingles?
10% for a simple gable roof, 15% for hips, valleys and dormers. Steep roofs waste more, because cutting and handling is harder.
Related calculators
Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.