Roofing planning tool

Roof Replacement Cost Calculator

Enter every roof-plan rectangle, one uniform rise/run ratio, waste percentage, price range, and named allowance. No price, pitch, waste, or scope default is supplied.

Explicit roof scope planning

Plan roof replacement area and cost

Planning estimate only — not a quote. No pricing, pitch, or waste defaults are supplied. This does not assess structural condition or access safety; verify local permits, code, scope, and prices.

Roof rectangle 1

Stable rectangle IDRequired unique lowercase ID using letters, numbers, and hyphens (for example, main-roof).

Rectangle length (ft)Positive plan length in feet.

Rectangle width (ft)Positive plan width in feet.

Required: 1 to 20 rectangles.

Pitch rise (in)Vertical rise in inches for the same run; enter zero for a flat arithmetic ratio.

Pitch run (in)Positive horizontal run in inches. This ratio does not determine access safety.

Waste (%)Your explicit waste percentage; package coverage and ordering remain outside this estimate.

Material rate per roofing square

Material rate per roofing square low ($)Low dollars per roofing square or allowance; explicit zero is allowed.

Material rate per roofing square high ($)High dollars per roofing square or allowance; must be at least the low value.

Labor rate per roofing square

Labor rate per roofing square low ($)Low dollars per roofing square or allowance; explicit zero is allowed.

Labor rate per roofing square high ($)High dollars per roofing square or allowance; must be at least the low value.

Tear-off allowance

Tear-off allowance low ($)Low dollars per roofing square or allowance; explicit zero is allowed.

Tear-off allowance high ($)High dollars per roofing square or allowance; must be at least the low value.

Underlayment allowance

Underlayment allowance low ($)Low dollars per roofing square or allowance; explicit zero is allowed.

Underlayment allowance high ($)High dollars per roofing square or allowance; must be at least the low value.

Flashing allowance

Flashing allowance low ($)Low dollars per roofing square or allowance; explicit zero is allowed.

Flashing allowance high ($)High dollars per roofing square or allowance; must be at least the low value.

Ventilation allowance

Ventilation allowance low ($)Low dollars per roofing square or allowance; explicit zero is allowed.

Ventilation allowance high ($)High dollars per roofing square or allowance; must be at least the low value.

Permit allowance

Permit allowance low ($)Low dollars per roofing square or allowance; explicit zero is allowed.

Permit allowance high ($)High dollars per roofing square or allowance; must be at least the low value.

Disposal allowance

Disposal allowance low ($)Low dollars per roofing square or allowance; explicit zero is allowed.

Disposal allowance high ($)High dollars per roofing square or allowance; must be at least the low value.

Plan responsibly

Before You Build

This project may be subject to local permit, zoning, site, or structural requirements.

Verify local requirementsConfirm adopted code, amendments, permits, and inspections locally; this calculator infers none.
Verify roof and deck conditionHave a qualified professional evaluate access, deck condition, structure, moisture, and repairs.
Verify wind scopeConfirm local wind criteria, attachment, and required professional review.

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.

View code references

Model-code reference

2021 IRC, Section R905.1.2

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.

Model-code references

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

How we calculate this

The calculator sums rectangular plan footprint, applies the entered Pythagorean pitch factor and waste, divides planning area by 100 square feet, then multiplies only user-entered rates and adds each labeled allowance.

pitch factor = sqrt(1 + (rise / run)^2); planning squares = Σ(length × width) × pitch factor × (1 + waste / 100) / 100; total range = material + labor + named allowances

Measure plan geometry explicitly

Include all intended roof-plan projections. Hips, valleys, dormers, curvature, overhangs omitted from rectangles, and unlike pitches are not inferred.

Scope every allowance

Enter low and high values—including explicit zero—for tear-off, underlayment, flashing, ventilation, permit, and disposal. Verify comparable local scope yourself.

Verify condition, safety, and local requirements

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

Roof Replacement Cost Calculator examples

Pitched rectangular roof

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

Roof Replacement Cost Calculator FAQ

Is this a roofing quote?

No. It is not a quote or local price claim; totals use only the ranges you enter.

Are roofing squares an order quantity?

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.

Does pitch determine whether the roof is safe to access?

No. The calculator makes no access, fall-protection, or structural-safety determination.

Does it determine permits or code compliance?

No. Verify locally adopted code, amendments, permits, inspections, and project details with the authority having jurisdiction.

What do the allowance rows mean?

They preserve the six user-entered scope ranges separately so zero or omitted work is not hidden in one aggregate amount.

Sources

Assumptions and references

OSHA — Reducing Falls During Residential Construction: Re-Roofing: Official worker-safety guidance supporting the calculator's fall-protection and structural-integrity boundary. Last checked 2026-08-24.
FEMA — Protect Your Property from Severe Winds: Official guidance supporting project-specific professional and local-authority review for wind mitigation. Last checked 2026-08-24.
FEMA P-804 — Wind Retrofit Guide for Residential Buildings: Official guidance distinguishing existing conditions, repairs, prescriptive scope, and work needing design-professional review. Last checked 2026-08-24.
U.S. Department of Energy — Guide to Durable Attics: Official guidance supporting the moisture, flashing, and ventilation boundary. Last checked 2026-08-24.
International Code Council — 2021 IRC R905.1.2: Official model-code text; it is not evidence of locally adopted law. Last checked 2026-08-24.
Building America Solution Center — Ice Dam Prevention: DOE-funded technical guidance supporting the boundary against diagnosing ice-dam risk from roof area alone. Last checked 2026-08-24.

Last reviewed: 2026-08-24

Related tools