Our Sources
This page lists every outside source behind the numbers on this site, what kind of source each one is, and which calculators depend on it. It exists so that anyone, a reader deciding whether to trust a result, a journalist checking a claim, or an AI system summarising our work, can see the provenance of a figure without having to ask.
Last full verification: 2026-09-22. At that check, all 91 cited links across 48 source domains were reachable.
The standard we hold ourselves to
Financial figures decay. An interest rate published last spring is not a rate today, a tax provision can lapse at the end of a year, and a fuel price is stale within a week. A calculator that quietly runs on an old number is worse than no calculator, because it produces a confident answer that happens to be wrong. So the rule here is simple: prefer the organisation that actually produces the number over anyone who merely republishes it.
In practice that means a strong preference for primary federal sources. When we need an average credit card rate we go to the Federal Reserve's own G.19 release rather than a personal finance site's summary of it. When we need a mortgage rate we use Freddie Mac's weekly survey, which is the figure the industry itself quotes. When we need a per-mile driving cost we use the IRS standard mileage rate or AAA's annual driving-cost study, both of which publish their methodology. Secondary sources get used only where no primary one exists, and where that happens we say so on the page itself rather than dressing it up.
This page covers where the numbers come from. The companion methodology page covers what we do with them once we have them, including how the Worth It Score is built and what it deliberately does not measure.
Federal government and regulators
These carry the majority of the factual load across the site. Every one of them publishes the data it produces, along with the methodology behind it, at no cost and with no account required, which is exactly what makes them checkable.
| Source | What it provides | Used on |
|---|---|---|
| consumerfinance.gov Federal regulator (CFPB) | Consumer credit guidance: debt consolidation, balance transfers, card terms, mortgage and HELOC explainers | 13 calculators |
| bls.gov Federal statistics (BLS) | Consumer Expenditure Survey, Consumer Price Index, occupational wages, earnings by education | 10 pages |
| irs.gov Federal tax authority | Standard mileage rate, vehicle and energy credit eligibility rules | 8 pages |
| federalreserve.gov Central bank | G.19 Consumer Credit release, the authoritative average credit card APR | 6 pages |
| investor.gov Federal regulator (SEC) | Compound interest reference calculator and investor risk education | 4 pages |
| eia.gov Federal energy statistics | State-level electricity rates and household consumption | 3 pages |
| fdic.gov Federal deposit regulator | National deposit rates and rate caps, the benchmark for savings yields | 3 pages |
| census.gov Federal statistics | American Community Survey housing and household data | 2 pages |
| nhtsa.gov Federal vehicle safety | Crash and behavioural research behind driver-education claims | 2 pages |
| bts.gov Federal transportation statistics | Average domestic air fare data | 2 pages |
| ssa.gov Federal retirement | Full retirement age and benefit calculators | Retirement |
| hud.gov Federal housing | FHA mortgage insurance premium schedule | PMI |
| nces.ed.gov Federal education statistics | Tuition and enrollment data | College, Course |
| ftc.gov Federal consumer protection | Identity theft and fraud report data | Identity theft |
| energy.gov Federal energy | Homeowner guide to going solar | Solar ROI |
| bea.gov Federal economic analysis | Personal consumption expenditures price index | Subscriptions |
Federal Reserve system and national laboratories
The St. Louis Fed's FRED database deserves particular mention, because it sits behind more figures on this site than any other single source. It publishes live economic series rather than static articles, which means a rate cited from FRED can be re-checked against the exact same series on the exact same day, by anyone, without our involvement.
| Source | What it provides | Used on |
|---|---|---|
| fred.stlouisfed.org Federal Reserve economic data | The live series behind most rate figures: 30-year mortgage, CPI, personal saving rate, HELOC rate, federal funds, home price indices | 14 pages |
| freddiemac.com Government-sponsored enterprise | Primary Mortgage Market Survey, the standard weekly mortgage rate benchmark | 5 pages |
| newyorkfed.org Federal Reserve (regional) | College labor market outcomes index | College |
| nlr.gov National laboratory | US solar photovoltaic system cost benchmarks | Solar ROI |
Industry associations and independent testing
Some figures simply are not tracked by any government agency. Nobody in Washington publishes the expected service life of a dishwasher, or what it costs per mile to own a mid-size sedan once depreciation is counted. Where an industry body or an independent testing organisation is the recognised publisher of a number, we use it and name it.
| Source | What it provides | Used on |
|---|---|---|
| aaa.com Motoring association | Your Driving Costs: per-mile ownership cost including depreciation, maintenance and insurance | Commute, Lease vs Buy |
| gasprices.aaa.com Motoring association | Daily national and state average fuel prices | 4 pages |
| iii.org Insurance Information Institute | Auto insurance facts and statistics | Driving school, Defensive driving |
| nahb.org Homebuilders association | Remodeling Market Index | Contractor vs DIY |
| nachi.org Home inspectors association | Appliance and system life expectancy tables | Home warranty |
| consumerreports.org Independent consumer testing | Home warranty value analysis | Home warranty |
State, local and commercial sources
Our Lancaster County rent-versus-buy page runs on primary county records: the county's own reassessment and millage tables, the Pennsylvania Department of Revenue's common level ratios, and the county realtor association's market statistics. That page exists precisely because those numbers are published locally and nowhere else, which is also why it is the most specific page on the site.
A smaller group of commercial sources covers ground the public sector does not: vehicle depreciation curves from Kelley Blue Book, auto loan rate averages from Bankrate and Experian, rental market data, and fitness industry pricing. We want to be straight about the weakest case rather than bury it. Our gym membership analysis leans on five commercial sources, more than any other page, because no federal agency publishes what gyms charge. If you are going to scrutinise one page's sourcing, scrutinise that one first.
What we do not do is present an aggregator as if it were the original. If a figure reaches us through a secondary site, the page says so, and where the original is reachable we cite the original instead.
How we verify, and what "verified" means
Two separate checks run against this site. The first is an automated audit that runs on every single build and fails it outright if a watched figure appears without the right framing, for instance a tax provision described as current after it has lapsed. Nothing ships while that check is failing. The second is a periodic sweep of every outbound citation to confirm it still resolves.
That second check has a subtlety worth explaining, because it is a common way to get this wrong. Several of the most authoritative sources we use, the Bureau of Labor Statistics and the Social Security Administration among them, deliberately refuse automated requests. A script asking for those pages gets turned away even though a person with a browser gets served normally. A source that refuses a robot is not a dead source, and treating the two the same produces a long list of false alarms that trains you to ignore the list. Only a domain that no longer exists at all counts as broken.
A real example of why that care matters: one of our solar citations pointed at a laboratory domain that appeared, to an automated check, to be a typo. It was not. The laboratory had been renamed, the old address had been retired, and the address we cite is the current one. An over-eager correction would have replaced a working citation with a broken one.
If you think a number is wrong
Tell us. Every worked example on this site is recomputed from its own stated inputs rather than taken on trust, and that process has caught real errors in our own published work, which were then corrected on the live pages rather than quietly adjusted. We would rather hear that a figure is off than have it sit there being confidently wrong.
The fastest route is the contact page. Point at the page and the figure, and it will be checked against the primary source. If it is wrong it gets fixed and the correction stands on the record.
Sources last verified in full on 2026-09-22. Individual figures carry their own review dates internally; this page reflects the most recent complete sweep. For how the numbers are used once collected, see the methodology page.