How our estimates are calculated
What this page explains. Every cost range on Home Repairs Estimator is produced by a deterministic formula, not a lookup table and not a machine-learning model. This page describes how the numbers are computed, what data they are based on, and what they do and do not represent. If you came here from an estimate and want to know "where did that number come from," you are in the right place.
The short version. A national baseline for each tool is computed from published contractor and industry data. The baseline is then adjusted by a city-tier multiplier that reflects local labor and material cost variation. The result is a planning range — a low and high bound meant to help you sanity-check quotes from real contractors. It is not a contractor quote, not a guaranteed price, and not a recommendation to hire any specific provider.
For each of the 23 tools in the catalog, we maintain a deterministic formula that takes the inputs you enter (home size, system type, project scope, etc.) and produces a low-high cost range. The formulas are anchored to publicly available industry data:
- HVAC — base replacement and repair costs anchored to published industry cost references, adjusted by system type (heat pump, central AC, furnace-plus-AC) and efficiency tier (basic, mid, high). City-tier multipliers from HSA's published methodology.
- Solar — installed cost per watt anchored to NREL Q4 2024 residential solar benchmarks (approximately $3.00/W pre-incentive), adjusted for shade, rate tier, and battery storage. The displayed range does not assume a federal residential solar credit for 2026 cash/loan purchases.
- Roofing, plumbing, electrical, flooring, window replacement, and other verticals — each anchored to published industry averages with documented assumptions in the source code. The formulas are deterministic and reviewable.
How calculator inputs are handled. Calculators run in your browser by default. If you choose to create a shareable estimate link, the estimate details needed for that link are sent to HSA and stored temporarily so the link can be opened later. Creating or viewing an estimate does not send your project to contractors, and HSA does not ask for a phone number to show a range. See our privacy policy for details on what is and is not collected.
The national baseline is a starting point, not a final answer. Cost of living, labor rates, and material availability vary significantly by metro area. We apply a city-tier multiplier to the national baseline based on which tier a city falls into:
- Low-tier markets (approximately 0.85× the national baseline) — smaller metros with lower cost of living, less expensive labor markets, and lower permit fees.
- Mid-tier markets (approximately 1.00× the national baseline) — the reference tier. Covers most mid-sized US metros.
- High-tier markets (approximately 1.15–1.25× the national baseline) — major coastal metros and high cost-of-living regions where labor rates, permit fees, and equipment availability push contractor pricing up.
The tier assignment for each city is deterministic and visible in the source (src/catalog/cities.json and related files). Tier assignments are informational only — they are a planning aid, not a claim about any specific contractor's pricing in your area.
Is: a conservative low-to-high bound meant to help you evaluate quotes from real contractors. If a contractor quotes you below the low end, ask what is excluded. If a contractor quotes you above the high end, ask for a line-item breakdown.
Is not: a contractor quote, a binding price, an appraisal, an insurance estimate, or a guarantee. Home Repairs Estimator does not provide any services directly and is not a party to any transaction between you and a contractor.
Why the range is wide. Contractor pricing in home services commonly varies by 25–40% between providers for the same scope of work. This reflects differences in overhead, labor availability, material sourcing, warranty terms, and profit margin — not poor workmanship. A planning range that is too narrow would give you false precision.
The formulas and data sources are in the open: the calculation functions live in the publicly-served JavaScript that runs in your browser. If you want to see how a specific number is derived, open a calculator, adjust the inputs, and watch the range change. Each input maps to a specific multiplier in the formula.
If you find a calculation that looks wrong or want to submit a correction, contact us at contact@homerepairsestimator.com.
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