Data sources & update log

Everything on this site traces to a primary government source. This page lists each dataset, what it feeds, and when our copy was last refreshed. How the numbers are turned into results is documented in the methodology.

Primary dataset

Additional CPI series

Category breakdowns, core inflation, and the current inflation rate use these companion series, all CPI-U, U.S. city average, not seasonally adjusted, fetched in the same monthly refresh:

• CUUR0000SA0L1E: Core (all items less food & energy), monthly + annual, 1957–
• CUUR0000SAF1: Food, 1913– · CUUR0000SA0E: Energy, 1957–
• CUUR0000SAH: Housing, 1967– · CUUR0000SAM: Medical care, 1935–
• CUUR0000SAA: Apparel, 1914– · CUUR0000SAT: Transportation, 1935–
• CUUR0000SAR: Recreation, 1993– · CUUR0000SAE: Education & communication, 1993–

Year-context facts

The "what things cost" figures on year pages come from the primary source for each series, cited at the bottom of every page that uses them:

• Median household income: U.S. Census Bureau, Current Population Survey
• Gasoline prices: U.S. Energy Information Administration
• Median home prices: U.S. Census Bureau new residential sales
• Federal minimum wage: U.S. Department of Labor
• First-class postage: USPS historical rate tables

What happens on each update

1. The new CPI figures are pulled from the BLS API on release day.
2. Automated checks verify there are no gaps or implausible jumps, and that the new dataset is at least as complete as the current one; a failed check keeps the previous data live.
3. Every page on the site is rebuilt so calculator results, tables, and charts all reflect the same vintage of data; there is no cache of stale numbers. A release page for the new month is generated in the same build.

Past vintages aren't discarded: every refresh is a version-controlled commit, so any prior month's dataset can be reconstructed exactly.

Update log

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