Input Parameters
Example Data Table
Click Load to prefill inputs, then press Calculate.
| # | Length (ft) | Width (ft) | Overhang (in) | Pitch | Waste (%) | Ridge (ft) | Hips (ft) | Valleys (ft) | Starter LF | Action |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 40 | 30 | 12 | 6 | 10 | 40 | 0 | 20 | 140 | |
| 2 | 55 | 28 | 10 | 7 | 12 | 22 | 36 | 40 | 166 | |
| 3 | 32 | 26 | 8 | 4 | 8 | 32 | 0 | 0 | 116 |
Starter LF defaults to 2×length + 2×width; override for complex edges.
Example of Using the 3-Tab Shingle Calculator
Example: 40 ft × 30 ft house, 12 in overhangs, 6/12 pitch, 10% waste, 40 ft ridge, 0 ft hips, 20 ft valleys, standard coverage.
- Select “From dimensions and pitch”.
- Enter length 40, width 30, overhang 12, pitch 6.
- Set waste to 10% or use “Standard hip / dormer”.
- Enter ridge 40, hips 0, valleys 20; starter ≈ 140 ft.
- Click Calculate to view squares, bundles, nails, and costs.
This scenario produces roughly 16.5 squares and around 55 bundles, including starter and ridge materials, depending on chosen coverage values.
What Are 3-Tab Shingles?
3-tab shingles are lightweight, strip-style asphalt shingles with three cut-out tabs. They offer consistent exposure, simple installation, and predictable coverage, making them ideal for calculators that estimate squares, bundles, and waste precisely.
Typical 3-Tab Shingle Coverage and Bundle Math
A standard 3-tab bundle covers about 33.3 square feet of field area. Three bundles usually cover one roofing square (100 square feet). This calculator multiplies waste-adjusted roof area by coverage to compute field, ridge, and starter bundles.
Choosing the Right Waste Percentage and Complexity
Simple gable roofs often need 5–8% waste, while hips, valleys, and dormers can require 10–20%. Use the complexity presets or custom input so the calculator reflects real cutting losses for your specific project.
Formula Used
- Slope factor:
SF = √(1 + (rise/12)²). - Effective length:
Lₑ = L + 2×overhang/12; Effective width:Wₑ = W + 2×overhang/12. - Plan area:
Aₚ = Lₑ × Wₑ. - Roof area:
A = Aₚ × SF(rectangular gable/hip approximation). - Waste-adjusted area:
Aʷ = A × (1 + waste%/100). - Squares:
Squares = Aʷ / 100. - Field bundles:
Bundles_field = ceil(Aʷ / coverage_per_bundle). - Ridge/hip bundles:
Bundles_ridge = ceil((ridge + hips) / ridge_coverage_per_bundle). - Starter bundles:
Bundles_starter = ceil(starter_LF / starter_coverage_per_bundle). - Total bundles:
Total = Bundles_field + Bundles_ridge + Bundles_starter. - Shingles (approx):
Shingles ≈ Total × 21; Nails:Nails = Shingles × nails_per_shingle. - Underlayment rolls:
Rolls_ul = ceil(Aʷ / ul_coverage). - Ice & water rolls:
Rolls_iw = ceil(IW_area / iw_coverage). - Nail boxes:
Boxes_nails = ceil(Nails / nails_per_box).
How to Use This Calculator
- Select input mode: dimensions with pitch or known roof area.
- Enter length, width, overhang, pitch, and roof complexity or waste.
- Add ridge, hips, valleys, and confirm coverage values per bundle.
- Set starter length or let the calculator estimate perimeter starters.
- Enable underlayment, ice & water, and nail box estimates if needed.
- Optionally enter pricing to see material cost breakdowns.
- Click Calculate, then export results as CSV or PDF.
Results
| Effective length × width | – ft |
|---|---|
| Slope factor | – |
| Plan area | – sq ft |
| Roof area | – sq ft |
| Waste-adjusted area | – sq ft |
| Squares | – |
| Field bundles | – bundles |
| Ridge+hip bundles | – bundles |
| Starter bundles | – bundles |
| Total bundles | – bundles |
| Approx shingles | – pcs |
| Nails needed | – pcs |
| Underlayment rolls | – rolls |
| Ice & water rolls | – rolls |
| Nail boxes | – boxes |
| Estimated bundles cost | – |
| Total estimated material cost | – |
Values rounded; verify coverage and codes with manufacturers and local standards.
Add Result to Session Table
| Label | Squares | Total bundles | Est. cost |
|---|
Notes
- Coverage values vary by manufacturer; always check technical data sheets.
- Ridge caps from 3-tab assume ~5″ exposure and three caps per shingle.
- Starter coverage assumes cutting full shingles; factory starters differ.
- This tool estimates materials only; confirm with a professional roofer.