Sources and licenses
Last updated: November 2026
Our calculators are built from public data and standard geometry. This page lists each source, what we use it for and its license. Naming an agency does not mean it endorses this site, and we never use agency logos, seals or emblems.
| Data | Source | Used for | License |
|---|---|---|---|
| Hourly wages by trade and state (25th, 50th, 75th percentile) | U.S. Bureau of Labor Statistics, Occupational Employment and Wage Statistics (OEWS), May 2025, state and national files | The labor line of every cost calculator; the labor rate pages | Public domain; BLS asks for citation. bls.gov copyright information page |
| Producer Price Indexes: construction materials, concrete products, lumber, gypsum products, asphalt felts and coatings, architectural coatings | U.S. Bureau of Labor Statistics, Producer Price Index, public API (latest month used: 2026-09) | Bringing survey costs to current prices; the construction inflation calculator | Public domain |
| Home improvement job costs by type and region | U.S. Census Bureau, American Housing Survey 2023, national public use file (project and household files) | The "what households paid" benchmarks on project cost pages. Our calculation: weighted median and middle half of professional jobs, only cells with 50 or more jobs | Work of the U.S. government (17 U.S.C. 105) |
| Price per square foot of new single-family houses, by region | U.S. Census Bureau, Survey of Construction, Characteristics of New Housing (2025) | The cost to build a house calculator | Work of the U.S. government (17 U.S.C. 105) |
| Room air conditioner sizing chart; water heater first-hour method; insulation guidance | U.S. Department of Energy (Energy Saver) and U.S. Environmental Protection Agency guidance | Heating and cooling calculators, R-value pages | Public domain; DOE asks for acknowledgement |
| Common residential code limits (riser, tread, headroom, 4 in sphere, guard height, attic vent ratio) | The model residential code used in most U.S. states, cited as numbers only | Stair, deck stair, baluster and attic ventilation calculators | Facts only; the code text is copyrighted and not reproduced. Your local code may differ |
| Typical material values (bag yields, coverage, densities, units per square foot) | Trade association technical notes, government handbooks and university extension publications, listed on our method page | All quantity calculators | Facts, written in our own words; ranges, not any brand's figure |
| Fonts | Spline Sans and Spline Sans Mono, served from our own server | All pages | SIL Open Font License 1.1 |
| Site code | Astro (static site generator) | Building the pages | MIT |
What we do not use
- Store or manufacturer prices and calculators. Material prices on this site are always the ones you type in.
- Paid cost databases or contractor directories.
- Structural design data: we do not size beams, joists, footings or rebar for loads.
Updates
The price indexes are refreshed every month, the wage data each spring when BLS publishes a new year, and the housing survey figures when Census releases the next survey. Each page shows when it was last reviewed. If you spot a mistake, email [email protected].