Every estimate starts with a quantity model, applies a unit-cost range, adjusts for project choices, and ends with a range-only budgeting result.
1. Estimate quantity first
Each calculator starts by estimating the project quantity that drives cost. The quantity model changes by project type.
Roof: footprint and pitch produce estimated roof area and roofing squares.
Windows: window count drives the base quantity.
Concrete slab: length, width, and thickness produce cubic yards.
2. Apply a baseline range
The MVP uses manually curated US baseline ranges. These ranges are intended for planning and comparison prep, not final bids.
Each calculator has low, typical, and high unit-cost assumptions.
The cost-data review date is shown on each calculator page.
No paid cost database has been copied into the MVP.
3. Adjust for scope and complexity
Material, scope, access, demolition, fixture level, finish level, and project complexity can materially change the estimate range.
Remodel pages use scope tiers instead of pretending to produce a contractor bid.
Exterior pages adjust for material, access, and removal assumptions.
Concrete and roof pages show quantity outputs so the formula is visible.
4. Use broad region factors
v0 uses broad US region factors. It does not provide ZIP-level precision, local contractor availability, permit-specific pricing, or site-condition adjustments.
The region selector is a coarse multiplier, not a local price quote.
Actual costs vary by labor market, material availability, contractor schedule, and permit requirements.
Future versions may add better state or region tables if the project earns enough usage signal.
5. Explain what is missing
Each calculator lists common exclusions and when to call a licensed professional. This is part of the estimate, not a legal footnote.
Hidden damage, code upgrades, structural repairs, and engineering are not included unless stated.
Insurance claims, tax credits, financing, and permit decisions require separate review.
Users should compare 2-3 local written quotes before hiring.
The output is intentionally a range because home projects are shaped by local labor, site conditions, materials, and scope changes.
Start with a calculator
Each calculator page explains its inputs, estimate range, formula, exclusions, and professional boundary.