Our Cost Estimation Methodology
A transparent look at where our numbers come from, how estimates are built, and how often they change. No black box: every number on this site traces back to a public data source and a stated formula.
How our estimates are calculated (quick answer)
Every estimate = Labor (all-in billed trade rate × task hours) + Materials (tiered retail unit prices × project quantity) + Supplies & disposal, with a regional cost adjustment applied to the labor component (state parity or ZIP-level wage data). These are direct costs: general contractor overhead & profit is not included — if a general contractor supervises the job, expect roughly 10–22% more, depending on the trade. Estimates are informational planning ranges — not quotes.
Data Sources
| Source | What it provides | Cadence |
|---|---|---|
| U.S. Bureau of Labor Statistics — OEWS ↗ | Occupational Employment and Wage Statistics for 15+ construction and home-service occupations. Provides the hourly wage baseline for every trade (carpenter, electrician, plumber, roofer, HVAC tech, general laborer) at national, state, and metropolitan levels. | Annual (May release) |
| U.S. Census Bureau — ACS ↗ | American Community Survey housing stock, median home values, and median home size by state — used to set typical project scale (e.g. average kitchen size, roof area) so estimates match real housing stock instead of generic assumptions. | Annual |
| Retail Material Pricing | Material unit costs aggregated from major home improvement retailers (Home Depot, Lowe’s) and manufacturer price lists. Three tiers — budget, standard, premium — reflect real product spreads within each category. | Periodic aggregation |
| BLS Regional Price Parities ↗ | Regional price parity and cost-of-living data used to build state cost multipliers and ZIP-level adjustments, so the same project is priced correctly across markets. | Annual |
The Estimation Formula
Estimate = Labor + Materials + Supplies + Disposal
where Labor = all-in billed trade rate × regional factor × task hours (payroll taxes, workers’ comp, insurance and overhead already inside the billed rate). General contractor overhead & profit is excluded from the total — each calculator shows the range to add if a GC supervises the job.
Labor hours by task
Each service defines labor effort per unit of work (hours per sq ft, per fixture, per system) calibrated against industry production rates. A minimum-hours floor keeps small jobs realistic (trip charge + setup dominates).
Trade wage rate
BLS OEWS median hourly wages by occupation, converted to all-in contractor billed rates (payroll taxes, workers’ comp, liability insurance, vehicle, tools and overhead included), inflated to current year, and scaled by a trade specialty multiplier (licensed trades bill above general labor). The conversion multiple is about 2.8× on the BLS wage level: the OEWS May 2025 mean hourly wage for construction and extraction occupations ($31.42) is the basis of our $88/hour national billed rate. BLS publishes wages, not billable rates — the multiple is our modeling assumption, not a BLS figure.
Material tiers
Budget / standard / premium unit prices from aggregated retail pricing. The quality slider moves within these real product spreads — not arbitrary percentages.
Project scale
Typical project size from Census housing data (average bathroom square footage, roof area, kitchen size). Your quantity input overrides the baseline when you know your project.
Regional adjustment
State-level labor cost factors from BLS price parity data, applied to the labor component only — materials are priced nationally. ZIP-level refinement uses metropolitan wage tables for 30 major metros, so the same project prices correctly in Boise vs. San Francisco.
Seasonal factor
Seasonal demand sensitivity (0–20% depending on trade) applied to outdoor and HVAC work — contractor busy seasons move real quotes.
Update Cadence & Review Process
📅 Refresh schedule
- National service ranges: reviewed against source data with each BLS OEWS release.
- Wage tables: re-baselined when BLS publishes new OEWS figures (annual).
- Material prices: refreshed periodically as retail prices move.
- Full dataset audit: each service is cross-checked so state and city prices apply the regional labor factor to the labor component only — the resulting total uplift is smaller than the raw factor, and the exact percentage is shown on every state page.
🔍 Quality gates
- Every calculator estimate passes a market-range sanity check before display.
- State page numbers derive from the same engine as calculator outputs — one source of truth.
- Prices that fail verification are flagged and excluded until corrected.
- Full data disclaimer →
Limitations
Our model prices typical projects in typical conditions. It does not price structural surprises, historic homes, code-triggered upgrades discovered mid-project, or custom work outside standard trade practice. BLS OEWS measures occupational wages — a labor input — not final project prices; our formula combines it with material costs and stated assumptions to produce an estimate range. Results are planning ranges, not quotes.
Corrections
Spotted a number that looks wrong? We fix verified errors quickly and log the change. Email support@homeservicecost.com with the page URL and what you observed.
Reviewed by the HomeServiceCost Research Team. Our team analyzes pricing data from the U.S. Bureau of Labor Statistics, Census Bureau ACS surveys, and major home improvement retailers to produce accurate cost estimates. This guide was last reviewed and updated on August 20, 2026.
Methodology: Cost ranges are calculated using regional labor multipliers, material price indices, and project complexity factors. Data is re-baselined when BLS publishes new OEWS figures (annual).