Updated
Data sources
Every dataset in use, with where it came from, when we retrieved it, what licence it carries, and what it cannot tell you. Figures we could not source are listed here as assumptions rather than quietly presented as data.
Federal statistics
The backbone of these calculators is public data published by United States federal agencies. It is authoritative, updated on a known schedule, and free of licensing restrictions as a work of the US government. We cache and normalise it rather than querying it live, so results stay reproducible and the site has no runtime dependency on an external service.
electricity-prices
primaryv2026.06- Source
- U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A — Average Price of Electricity to Ultimate Customers by End-Use Sector, by State
- Period
- June 2026
- Retrieved
- 2026-09-11
- Licence
- U.S. Government work, public domain
- Limitations
- Residential sector average retail price. State averages blend all utilities and rate classes in the state; an individual household bill can differ substantially, especially in deregulated markets and for customers on time-of-use tariffs.
trade-wages
primaryv2025.05- Source
- U.S. Bureau of Labor Statistics, Occupational Employment and Wage Statistics (OEWS), State cross-industry estimates
- Period
- May 2025
- Retrieved
- 2026-07-31
- Licence
- U.S. Government work, public domain
- Limitations
- Hourly mean wage (H_MEAN) for each trade. These are employee wages, not billed contractor rates. Billed rates are derived in the engine by applying a documented burden-and-overhead multiplier; see docs/calculator-methodology.md.
climate
mixedv2026.07- Source
- NOAA Climate Prediction Center, population-weighted daily degree days (StatesCONUS), 5-year mean. Alaska and Hawaii from U.S. Energy Information Administration State Energy Data System indicators.
- Period
- 2021–2025 mean
- Retrieved
- 2026-07-31
- Licence
- U.S. Government work, public domain
- Limitations
- Degree days are population-weighted state means over a 5-year window, which smooths single-year weather swings. IECC zone is DERIVED from HDD65 threshold bands and is the dominant zone for the state only; IECC assigns zones by county and large states span several. Alaska and Hawaii are not in the NOAA CONUS product and use EIA SEDS values. The District of Columbia inherits Maryland.
zip-prefixes
referencev2026.07- Source
- United States Postal Service ZIP Code prefix allocations by state
- Retrieved
- 2026-07-31
- Licence
- Public reference data
- Limitations
- Inclusive ZIP3 ranges. A handful of ZIP3 prefixes straddle state lines for delivery reasons; this table returns the dominant state. Territories other than Puerto Rico are not mapped and fall back to the national estimate.
material-baselines
assumptionv2026.07.1- Source
- PlainTotal editorial baseline, reviewed against publicly advertised supplier pricing, manufacturer specifications, and published trade guidance
- Period
- 2026 national baseline
- Retrieved
- 2026-07-31
- Licence
- PlainTotal original work
- Location
- /methodology
- Limitations
- These are NOT published statistics. No public agency publishes a national residential material price index at this granularity, and proprietary construction cost databases cannot be reproduced. Each figure is a documented editorial baseline for material only, excluding labor, delivered to a metropolitan supply yard, before regional adjustment and before sales tax. They are the least certain inputs in the project calculators and are the first thing to replace with surveyed data. Labor hours are crew-hours for a competent crew under normal conditions.
appliances
secondaryv2026.07.1- Source
- Typical power draw compiled from U.S. Department of Energy appliance guidance, ENERGY STAR product criteria and certified product data, and manufacturer nameplate specifications
- Period
- 2026
- Retrieved
- 2026-07-31
- Licence
- Compiled reference; underlying federal guidance is public domain
- Limitations
- Running watts describe draw while actively operating, not standby. Appliances that cycle on a thermostat (refrigerators, freezers, window air conditioners) are modeled with a duty cycle rather than continuous operation, because nameplate watts times hours would overstate their use several-fold. Individual units vary widely by age, size, efficiency tier, and setting; treat these as class averages.
assumption-registry
assumptionv2026.07.4- Source
- PlainTotal assumption calibration. Each entry records the range of values observed across multiple defensible references, the baseline selected, and why.
- Period
- 2026 review
- Retrieved
- 2026-07-31
- Licence
- PlainTotal original work
- Location
- /methodology
- Limitations
- This registry exists so no modelling judgement is invisible. Every entry that moves a user-facing number records the spread of values found across references, the figure selected, the reasoning, geographic applicability, confidence, risk, the date it was last checked, the review cadence, the supporting sources, and its known limitations. Entries with risk "high" are the ones most likely to be wrong and most consequential when they are. None of this is a published statistic — where a figure could be sourced from a statistical agency it lives in one of the primary datasets instead.
exterior-baselines
assumptionv2026.07.1- Source
- PlainTotal editorial baseline for exterior work, reviewed against publicly advertised supplier pricing, manufacturer specifications, and published trade guidance
- Period
- 2026 national baseline
- Retrieved
- 2026-07-31
- Licence
- PlainTotal original work
- Location
- /methodology
- Limitations
- These are NOT published statistics. As with the interior material baselines, no public agency publishes exterior material prices at this granularity and proprietary construction cost databases cannot be reproduced. Every figure is material only, delivered to a metropolitan supply yard, before regional adjustment and before sales tax. Labor rates are crew-hours or per-unit production rates for a competent crew in normal conditions. See docs/data-sources.md for the full limitation statement.
gasoline-prices
primaryv2026.09.1- Source
- U.S. Energy Information Administration, Weekly Retail Gasoline and Diesel Prices — regular grade, all formulations, by region and selected state
- Period
- Week of 2026-09-07
- Retrieved
- 2026-09-11
- Licence
- U.S. Government work, public domain
- Limitations
- EIA publishes weekly retail gasoline prices for the nation, for each Petroleum Administration for Defense District (PADD) sub-region, and for nine individual states. States EIA does not publish separately take their PADD sub-region price, which is the finest published geography available; every result discloses which of the two applied. Prices are a weekly snapshot and move faster than any other figure on this site, so every calculator that uses them lets you type in the price you actually paid.
auto-insurance
primaryv2026.07.1- Source
- National Association of Insurance Commissioners, 2023 Auto Insurance Database Average Premium Supplement, Table 4 — Average Expenditure by State
- Period
- 2023
- Retrieved
- 2026-07-31
- Licence
- Published by the NAIC; figures reproduced with attribution
- Limitations
- Average expenditure is what insured drivers actually paid per insured vehicle, not a quoted premium: it already reflects the mix of coverages people buy in that state, including drivers who carry liability only. It is the most recent year the NAIC has published, so it lags current premiums — expenditures rose roughly 14% in the year this data covers, and the trend has not reversed. Treat it as a starting point and enter your own premium if you know it. Individual premiums vary enormously with driving record, credit-based insurance score where permitted, vehicle, garaging address, and chosen limits; a state average cannot predict any individual's rate.
vehicle-baselines
mixedv2026.07.1- Source
- Fuel economy anchored to the U.S. EPA Automotive Trends Report (model year 2024 real-world values); ownership cost components compiled from IRS Notice 2026-10 and IR-2026-29 standard mileage rates, U.S. DOE Alternative Fuels Data Center guidance, and editorial baselines where no agency publishes a figure
- Period
- 2026
- Retrieved
- 2026-07-31
- Licence
- Underlying federal publications are U.S. Government works in the public domain; the compiled baselines are editorial
- Limitations
- Two numbers here come straight from the EPA: the model year 2024 fleet-wide real-world average of 27.2 MPG and the truck SUV average of 25.7 MPG. The other class averages are editorial estimates positioned around those published anchors, and every one of them describes a NEW vehicle — the average vehicle actually on the road is roughly twelve years old and less efficient, which is why each class carries a range rather than a point. Depreciation, maintenance, tires, and registration are assumptions: no federal agency publishes them per vehicle, and the commercial datasets that do are licensed products we have not bought. Each is registered in the assumption registry with its observed range and rationale, and each is adjustable in every calculator that uses it.
employment-baselines
primaryv2026.09.1- Source
- U.S. Bureau of Labor Statistics, Employer Costs for Employee Compensation (June 2026); U.S. Department of Labor Wage and Hour Division, Fair Labor Standards Act overtime and Part 541 exemption regulations
- Period
- June 2026
- Retrieved
- 2026-09-11
- Licence
- U.S. Government works, public domain
- Limitations
- Compensation shares are the published BLS Employer Costs for Employee Compensation figures for June 2026 — employer cost per hour worked, which is what an employer spends rather than what an employee receives after tax. The Fair Labor Standards Act figures are the federal floor only. Many states set stricter rules, and no state rules are encoded here, so nothing in this dataset should be read as establishing what any particular worker is owed.
marketplace-fees
secondaryv2026.07.1- Source
- Published seller fee schedules from each platform: Etsy Fees & Payments Policy and Help Center, eBay Selling Fees help pages, Amazon Selling on Amazon fee schedule, Shopify pricing page, TikTok Shop US Seller University
- Period
- July 2026
- Retrieved
- 2026-07-31
- Licence
- Fee figures are factual rates published by each platform and are reproduced with attribution to their source
- Location
- https://www.etsy.com/legal/fees/
- Limitations
- Every platform's fee model is versioned separately and carries its own last-verified date and source link, because they change independently and often. Marketplace fees are the most volatile data on this site — a rate can change with a month's notice — so any result built on them is an estimate of what a payout would be under the rates recorded here, never a guarantee of what a platform will actually pay. Each rate is editable in the calculator. Where a figure could not be confirmed by directly retrieving the platform's page, that is recorded on the platform entry rather than glossed over.
What we could not source
Material and fixture prices are the honest gap. No public agency publishes a residential material price index at the granularity a cost calculator needs, and the commercial databases that do exist are proprietary and cannot be reproduced without a licence.
Rather than dress up estimates as data, those figures carry an assumption label everywhere they appear, including on the result itself. Replacing them with surveyed pricing is the highest-value improvement available to this project.
Update schedule
- Electricity prices — EIA publishes monthly; we refresh at least quarterly.
- Trade wages — BLS publishes annually each spring; we refresh within a month of release.
- Degree days — recomputed annually as a rolling five-year mean.
- Material baselines — reviewed at least annually, next due 2027-07-31.
Datasets are plain JSON with their metadata attached, so a refresh is a data change and a version bump rather than a code change.
Found a mistake?
Corrections are genuinely welcome, particularly from people in the trades who see these numbers every day. Please use the report incorrect data page.