Inputs
Typical architectural/3-tab: ~33.3 sq ft per bundle.
Starter roll coverage estimate; adjust to your product.
Common ridge cap bundle covers ~33 linear feet.
Use for valleys, dormers, intricate cuts beyond standard waste.
Roof Sections
Pitch factor uses factor = √(1 + (rise/run)²) per section.
Accessories, Components & Fees
Ice & water shield area from eaves, valleys, and rakes (by courses and width).
~2 inches overlap ≈ 0.17 ft.
NFA requirement is attic area divided by the chosen ratio. Balance ridge/soffit roughly 50/50.
Results
Total plan area: 0 sq ft
Pitch-adjusted area: 0 sq ft
Roofing squares: 0 squares
Main field bundles (with waste): 0 bundles
Starter bundles: 0 bundles
Ridge/hip bundles: 0 bundles
Underlayment rolls: 0 rolls
I&W shield rolls: 0 rolls
Valley metal pieces: 0
Drip edge pieces: 0
Sheathing sheets: 0
Nail boxes: 0
Ridge vent pieces: 0
Box vents: 0
Tear-off tonnage: 0 tons
NFA required: 0 sq in
Ridge NFA provided: 0 sq in
Soffit NFA provided: 0 sq in
NFA status: Check
Total bundles (rounded): 0 bundles
Costing (optional)
Materials subtotal: 0
Labor estimate: 0
Tax on materials: 0
Permit fee: 0
Delivery fee: 0
Dump fee: 0
Dump fee (per ton): 0
Contingency: 0
Grand total: 0
Example Data
These example roof sections match the Load Example button.
| # | Length (ft) | Width (ft) | Pitch rise | Pitch run | Plan area (sq ft) | Adj. area (sq ft) |
|---|---|---|---|---|---|---|
| 1 | 30 | 20 | 6 | 12 | 600 | 632.46 |
| 2 | 15 | 10 | 8 | 12 | 150 | 160.08 |
Formulas Used
- Plan area per section = length × width.
- Pitch factor = √(1 + (rise/run)²). For example, 6:12 ≈ 1.054.
- Adjusted area per section = plan area × pitch factor.
- Total adjusted area = sum of adjusted areas for all sections.
- Roofing squares = total adjusted area ÷ 100 (imperial) or ÷ 9.290304 (metric).
- Main field bundles = (total adjusted area ÷ coverage per bundle) × (1 + waste%).
- Starter bundles = total eave length ÷ starter coverage per bundle.
- Ridge/Hip bundles = (ridge length + hip length) ÷ ridge cap coverage per bundle.
- Underlayment rolls = (adjusted area ÷ roll coverage) × (1 + underlayment waste%).
- Ice & water rolls = ((eaveLen × width × eaveCourses) + (valleyLen × width × valleyCourses) + (rakeLen × width × rakeCourses)) ÷ roll coverage × (1 + waste%).
- Valley metal pieces = valleyLen ÷ (piece length − overlap).
- Drip edge pieces = (eave + rake) ÷ (piece length − overlap).
- Sheathing sheets = (adjusted area × replace%) ÷ (sheetLen × sheetWid).
- Nail boxes = (squares × nails per square) ÷ nails per box.
- Ridge vent pieces = ridge length ÷ (piece length − overlap).
- NFA required = planArea × 144 ÷ ratio; ridge/soffit ≈ required ÷ 2 each.
- Tear-off tons = squares × weight per square × layers ÷ 2000.
- Totals are rounded up to whole bundles/rolls/pieces/boxes for procurement.
How to Use
- Toggle units if you work in meters. Defaults use feet.
- Enter bundle coverage from the product datasheet or keep defaults.
- Add roof sections. Provide length, width, and the pitch rise/run.
- Set waste percentage and any extra complexity allowance as needed.
- Enter total eave, ridge, hip, rake, and valley lengths.
- Configure underlayment, ice & water at eaves, valleys, and rakes.
- Add valley metal, drip edge, nails, sheathing, and ventilation NFA.
- Include permit, delivery, dump fees, and tear-off tonnage if applicable.
- Click Calculate to get counts and costs; export CSV/PDF.
FAQs
It’s a widely used geometric approximation that closely matches manufacturer lookup tables for common roof pitches, suitable for estimating materials at planning and procurement stages.
In cold or high-wind zones, many specifications require extending protection at rakes. Set rake courses accordingly; the calculator adds area and rolls automatically.
Required NFA is attic area divided by 150 or 300. Provided NFA is computed from ridge and soffit lengths using their NFA per foot. Balance roughly half intake, half exhaust.
Tear-off tonnage estimates weight from squares, layers, and pounds per square. Use it to choose dumpster size and to budget per-ton disposal fees if charged.
Yes. Enable metric to display meters and square meters. Coverage per bundle and linear coverages automatically switch to metric defaults, which you can still override.
Materials, labor per square, taxes, permit, delivery, dump flat and per-ton, and contingency are included. Add other line items to CSV/PDF as needed.