Roofing Calculator — Shingles & Bundles
Estimate roof area, roofing squares, shingles, underlayment, ridge cap, starter strip, nails, and cost.
Roofing quantity is based on measured roof-surface area or footprint area adjusted by roof pitch. The calculator converts order area into roofing squares, shingle bundles, underlayment, ridge cap, starter strip, nails, and an editable material cost.
1,341.64 sq ft measured roof · 15.4 roofing squares with 15% waste · 2 underlayment roll(s).
- Field shingles47 bundles
- Underlayment2 rolls
- Roofing nails4938 nails
- Hip and ridge cap2 bundles
- Starter strip2 bundles
Do not climb onto a roof to collect measurements. Use plans, safe ground measurements, or a qualified roofing professional.
Hips, valleys, dormers, penetrations, starter, flashing, ventilation, ice barrier, tear-off, local code, and the exact product system can change the order.
Coverage and nailing defaults are editable planning values. The selected manufacturer's instructions always take priority.
Step by step
- 1
Use safe ground, plan, or contractor measurements; never climb a roof solely to use this calculator.
- 2
Enter roof area directly or enter footprint dimensions and pitch rise, then add an allowance for cuts, valleys, hips, and complexity.
- 3
Replace every default package coverage with the values on the selected products and have a qualified roofer verify flashing, ventilation, deck condition, fastening, and code requirements.
Check the estimate before you buy
Estimate roof surface area, roofing squares, shingle bundles, underlayment, ridge cap, starter strip, nails, and shingle cost.
A 40 × 30 ft footprint with a 6-in-12 pitch has about 1,342 sq ft of roof surface before overhangs or complexity. With 15% waste, the order area is about 1,543 sq ft, or 15.43 roofing squares. At 33.33 sq ft per bundle, that rounds to 47 bundles.
How the calculation works
Footprint mode multiplies horizontal area by √(1 + (pitch rise ÷ 12)²). Direct-area mode uses the measured roof area. Waste is added before converting to 100-sq-ft roofing squares and dividing by each product's stated package coverage.
Roofing Calculator — Shingles & Bundles FAQ
Should I buy exactly the calculated amount of roofing materials?
Usually no. Cuts, spillage, breakage, uneven surfaces, batch matching, and package rounding can increase the order. Use the editable allowance and confirm the product label.
Why does the result round up?
Stores sell full bags, boxes, cans, rolls, panels, or pieces. The tool keeps the mathematical amount visible, then rounds the purchasing quantity up separately.
How many bundles are in a roofing square?
Many common shingles use about three bundles per 100-sq-ft square, but that is not universal. Enter the coverage printed for the exact bundle.
Does roof pitch increase roof area?
Yes. Footprint mode applies a slope factor from the pitch rise. Overhangs and individual roof-plane geometry must still be included separately.
Reference: GAF roofing-system planning worksheet. Results are practical estimates; complete labels, package directions, product specifications, and qualified professional advice take priority.