U.S. BLS CPI-U: Measure, Periods & Comparison Checklist

What this reference provides

The all-items, U.S. city-average CPI-U series is the basis of our downloadable historical snapshot and three U.S. calculators.

Measure and geography

Consumer Price Index for All Urban Consumers, not seasonally adjusted. Monthly observations describe the reference month, not an individual transaction date.

Period basis

Our snapshot contains 1,364 observed months from January 1913 to September 2026. October 2025 is unavailable; no synthetic value or annual-average replacement is inserted.

Boundaries

The national urban-consumer basket does not reproduce a household's own mix of rent, food, transport or debt payments. It is not an exchange-rate series or a contract-specific escalation rule.

A practical comparison task

Select the same two observed months in a primary-source download and our tool. Check the index levels, divide end by start and multiply the original amount. Keep the unrounded ratio until the final monetary rounding.

Keep the interpretation with the result

A missing intermediate observation does not prevent an endpoint calculation when both endpoints exist. It does prevent a complete continuous monthly path. Our table skips that month and the chart breaks there. A missing endpoint cannot be selected.

Primary source

BLS CPI inflation calculator and missing October 2025 observation — checked 17 October 2026. This page does not claim an authenticated test or a complete catalogue of the source’s data series.