How We Calculate Cost Estimates
CostPrism uses a multi-layer methodology to produce localized cost estimates across 49 cost categories, 50 states, and 50 major cities. This page describes our process in full.
National Baseline Establishment
For each cost category, we establish a national baseline average from multiple data sources. Baselines represent the typical cost for a standard scenario (e.g., a 2,000 sqft roof replacement with architectural asphalt shingles) under median national conditions.
Sources for national baselines vary by category:
| Category | Primary Source |
|---|---|
| Home Improvement (Roof, HVAC, etc.) | NAHB, NRCA, ACCA contractor surveys + BLS wage data |
| Auto & Homeowners Insurance | NAIC state filings, insurance commissioner data |
| Medical Procedures | CMS reimbursement schedules, provider billing surveys |
| Solar Installation | DOE / NREL benchmarks, Lawrence Berkeley National Lab data |
| Business Services (Payroll, LLC, etc.) | SHRM surveys, state fee schedules, market research |
| Legal (Divorce, etc.) | State bar surveys, court fee schedules, practitioner surveys |
State Cost Multipliers
Each state receives a cost multiplier (range: 0.72–1.58) that scales the national baseline up or down based on local conditions. The multiplier is a weighted composite of:
- •Labor cost index (40% weight): BLS mean hourly wages for relevant occupations (construction, healthcare, etc.) in each state relative to the national median
- •Material cost index (30% weight): Regional material costs including transportation, state sales tax on materials, and local supplier market concentration
- •Cost of living index (20% weight): C2ER Cost of Living Index by state, capturing business overhead and operational costs
- •Regulatory & permit factors (10% weight): State licensing requirements, permit fee schedules, and contractor density affecting competitive pricing
Sample State Multipliers
| State | Multiplier | vs. National |
|---|---|---|
| California | 1.48× | +48% above avg |
| Colorado | 1.12× | +12% above avg |
| Florida | 1.85× | +85% above avg |
| Hawaii | 1.68× | +68% above avg |
| Mississippi | 0.80× | -20% below avg |
| New York | 1.52× | +52% above avg |
| Ohio | 0.98× | -2% below avg |
| Texas | 0.98× | -2% below avg |
City-Level Adjustments
For our 50-city dataset, each city receives an additional adjustment layered on top of the state multiplier. City adjustments capture metro-area premiums or discounts:
- •Urban premium: Major metros (NYC, SF, LA, Chicago, Boston) carry 15–40% premiums above their state average due to labor market competition, permitting complexity, and higher operating costs
- •Secondary city discounts: Mid-sized cities often run 5–15% below their state average due to lower demand pressure and more competitive contractor markets
- •Climate factors: For HVAC, roofing, and insulation categories, extreme climate zones (humid subtropical, semi-arid) carry additional adjustments based on DOE climate data
Low / Average / High Range Calculation
For each estimate, we present a low-average-high range derived from the distribution of actual contractor bids and project invoices in the underlying data:
| Range | Represents |
|---|---|
| Low | 25th percentile — basic materials, competitive market, favorable conditions |
| Average | 50th–60th percentile — standard quality, typical market conditions |
| High | 85th percentile — premium materials, complex conditions, premium contractors |
Spread ratios: Low = Average × 0.68–0.75; High = Average × 1.30–1.55 (varies by category volatility)
Annual Update Process
All cost data is reviewed annually (typically Q1–Q2 each year). The update process includes:
- 1.Review new BLS Occupational Employment data (released annually)
- 2.Update material cost indices based on Producer Price Index (PPI) for relevant commodities
- 3.Cross-validate state multipliers against C2ER annual Cost of Living Index release
- 4.Update insurance baselines based on NAIC annual market report
- 5.Incorporate user feedback on significant local market deviations
Current dataset reflects June 2026 pricing conditions.
Known Limitations
- !Rural vs. urban within a state: Our state multipliers use state-level averages. Rural areas within a state may run 10–20% lower; dense urban cores may run 15–30% higher than our state estimate.
- !Real-time material price spikes: Lumber, copper, and asphalt prices can spike rapidly following supply disruptions. Our annual update cadence may not capture short-term price events.
- !Individual project complexity: Unique structural conditions, access challenges, or premium specifications can move costs significantly outside our ranges.
- !Insurance individual risk factors: Insurance premiums depend heavily on individual credit scores, claims history, property characteristics, and carrier-specific underwriting rules that our state averages cannot capture.