Roofing planning tool
Homeowner mode uses footprint dimensions, a pitch preset, material, and project context with sourced national installed planning ranges. Advanced assumptions retains exact rise/run, waste, split rates, and six allowances.
Roof replacement planning
Planning estimate only — not a quote. Start with sourced national installed ranges or inspect every raw assumption.
Plan responsibly
This project may be subject to local permit, zoning, site, or structural requirements.
Model code is not adopted local law: The cited IRC section does not establish locally adopted requirements.
Cost arithmetic only: This applies user-entered area and price arithmetic. It does not determine ice-barrier applicability, design structural work, verify installation, or establish compliance.
Not a quote: User-entered prices are not a bid, guarantee, or local-market claim.
Safety is outside the calculation: Area and pitch arithmetic cannot determine access, fall protection, structure, condition, or compliance.
Ice barriers for specified roof coverings: The model code addresses ice barriers in designated ice-forming areas. Verify local adoption, applicability, details, and exceptions.
Source: International Code Council — 2021 IRC R905.1.2 · Reviewed 2026-08-24
Local requirements may differ. A model-code reference does not confirm the code edition, amendments, zoning rules, or permit requirements adopted where the project is located.
2021 IRC, Section R905.1.2: Ice barriers for specified roof coverings. Source: International Code Council — 2021 IRC R905.1.2. Reviewed 2026-08-24.
Local requirements may differ. Verify the adopted code, amendments, zoning rules, and permit requirements with the local authority.
Methodology
The calculator sums rectangular footprint, applies the disclosed or entered Pythagorean pitch factor and waste, and divides by 100 square feet. Homeowner mode multiplies that area by a sourced installed range; Advanced can use user-entered installed or split rates and explicit allowances.
Include all intended roof-plan projections. Hips, valleys, dormers, curvature, overhangs omitted from rectangles, and unlike pitches are not inferred.
Homeowner mode prices the measured planning roof area with a sourced national installed range that combines material and labor.
Roofing quotes do not always include the same scope. Tear-off, underlayment, flashing, ventilation, disposal, and permits may be included or listed separately. Use Advanced assumptions if you already have local ranges for these items, and compare the same scope in each quote.
The result does not assess roof or deck condition, load capacity, moisture, fall safety, code, or permits. Verify locally adopted requirements and obtain qualified review.
Worked examples
A 40 × 30 ft plan at 6/12 with 10% entered waste produces 1,475.804865 sq ft of planning area before applying only the user's rates and allowances.
Common questions
No. Homeowner results use identified national installed planning ranges; Advanced may use user-entered overrides. Neither is a local price claim or quote.
No. A planning square here is planning area divided by 100 sq ft; package coverage, laps, starter, ridge, and manufacturer instructions remain outside the formula.
No. The calculator makes no access, fall-protection, or structural-safety determination.
No. Verify locally adopted code, amendments, permits, inspections, and project details with the authority having jurisdiction.
They preserve the six user-entered scope ranges separately so zero or omitted work is not hidden in one aggregate amount.
Sources
Last reviewed: 2026-08-24
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