Methodology

Overview

Prices alone don’t tell the full story. A gallon of gas cost $0.36 in 1970, but incomes were much lower too. BoomerPrices goes beyond raw dollar amounts by measuring what share of a household’s income each item actually consumed — then vs now. This “income share” approach reveals whether something has become genuinely harder to afford or just looks more expensive due to inflation.

Data Sources

All data comes from official U.S. government agencies and is publicly verifiable. We never use estimates, projections, or third-party calculations.

Bureau of Labor Statistics (BLS)

• CPI-U All Items (series CUUR0000SA0) — the Consumer Price Index for All Urban Consumers, used for inflation adjustment. Data from 1970 to present.
• Average price series — actual dollar prices for individual items (e.g. milk, eggs, bread, bacon, coffee, sugar, beer, ground beef, chicken) from the BLS average price program. Also includes utility prices like electricity per kWh and natural gas per therm. Only items with real dollar-amount data are included — we do not use CPI sub-indexes as price proxies.
• Regional CPI — separate CPI series for Northeast (CUUR0100SA0), Midwest (CUUR0200SA0), South (CUUR0300SA0), and West (CUUR0400SA0), plus regional housing and food sub-indexes. Used for regional inflation adjustment only.

Federal Reserve Economic Data (FRED)

• National median household income (series MEHOINUSA646N) — median household income in nominal (current-year) dollars, sourced from the Census Bureau’s Current Population Survey. Data from 1984 to present, with 1970–1983 from Census Historical Table H-6.
• State-level median household income (series MEHOINUS{STATE}A646N) — median household income per state in nominal dollars. Used when a user selects a state for regional affordability comparisons.
• Median home price (series MSPUS) — median sales price of houses sold in the United States.
• Crude oil & fuel prices — WTI crude oil spot price (MCOILWTICO), gasoline (APU000074714), and heating oil (DHOILNYH) from EIA and BLS data distributed via FRED.

U.S. Census Bureau

• Household income — the underlying source for national and state-level median household income data, collected through the Annual Social and Economic Supplements to the Current Population Survey. FRED serves as the distribution point.
• Median gross rent (ACS Table B25064) — national median gross rent (rent + utilities) from the American Community Survey 1-year estimates and decennial Census. All values verified via Census Bureau API.
• Median property tax (ACS Table B25103) — median real estate taxes paid on owner-occupied housing from ACS 1-year estimates. All values verified via Census Bureau API.

Other Federal Sources

• NCES (Digest of Education Statistics, Table 330.10) — average published tuition and fees at public and private nonprofit four-year institutions.
• CMS (National Health Expenditure Accounts) — per capita out-of-pocket healthcare spending; Medicare Part B standard monthly premiums.
• DOL (Wage and Hour Division) — federal minimum wage rate history.
• KFF (Employer Health Benefits Survey) — average annual employer-sponsored family health insurance premiums.
• USPS — first-class letter postage rates.

Data integrity policy

BoomerPrices only displays items with verifiable dollar-amount prices from government sources. We do not use CPI sub-indexes (e.g. “rent CPI” or “medical care CPI”) as price proxies, because index values are not prices and cannot be meaningfully compared as dollar amounts. If a reliable dollar-denominated series does not exist for an item, we do not include it.

How Comparisons Work

Every comparison follows a three-step calculation pipeline.

Step 1: Inflation adjustment

We convert historical prices into today’s dollars using the CPI-U index. The formula is:

This tells you what the old price would be in today’s dollars, accounting for the general change in price levels. But inflation adjustment alone misses changes in earning power — that’s where income share comes in.

Step 2: Income share

We calculate what percentage of annual median household income the item consumed in each year:

This is the core metric. If a gallon of milk took 0.05% of household income in 1980 and takes 0.06% today, that’s a measurable affordability shift — regardless of what happened to the dollar.

Step 3: Buying power ratio

Finally, we compare the income shares to produce a single ratio:

A ratio above 1.0 means the item takes a bigger bite out of income today. A ratio below 1.0 means it’s become more affordable relative to earnings. A ratio of exactly 1.0 means affordability hasn’t changed.

Wage Analysis

When comparing wage items (e.g. the federal minimum wage), the analysis shifts from “affordability” to “purchasing power.” A wage is income, not a cost, so the standard buying power ratio doesn’t apply.

Purchasing power change

We use the same CPI inflation adjustment, but frame the result differently. If the inflation-adjusted value of a historical wage is higher than the current wage, the wage has lost purchasing power. For example, $1.60/hr in 1970 equals ~$13.30/hr in 2025 dollars, but the actual minimum wage is $7.25 — a significant loss in real value.

Wage as % of median income

We compute what a full-time worker at the given wage earns annually (wage × 2,080 hours) and express that as a percentage of median household income. This shows how a minimum wage worker’s relative standing has changed over time.

Data Coverage & Limitations

• Year ranges: CPI data is available from 1970 onward. Income data covers 1970 to present (1970–1983 from Census Historical Table H-6, 1984+ from FRED).
• State-level income: State-level median household income is available for all 50 states + DC from 1984 onward (FRED). Prices are national — no state-level prices exist in government data for individual items. When a state is selected, affordability reflects that state’s actual median income against national prices.
• CPI methodology changes: The BLS has updated its CPI methodology multiple times since the 1970s (e.g., owner’s equivalent rent in 1983, geometric mean formula in 1999). These changes affect historical comparability. We use the published CPI values as-is without attempting to back-adjust.
• Income measure: We use median household income in nominal (current-year) dollars (MEHOINUSA646N). Because both prices and income are in nominal dollars, the income share ratio directly shows whether an item takes a larger or smaller bite of what households actually earned that year.
• Missing data: Not every item has price data for every year. When data is unavailable, the comparison returns null for those fields rather than estimating.

Data Freshness

BLS publishes CPI and average price data monthly. FRED updates income series annually (typically September for the prior year). BoomerPrices ingests new data periodically and uses annual averages for year-over-year comparisons. The most recent complete data year depends on when each agency publishes — there’s typically a 6–12 month lag for annual figures.