Statistics Bureau of Japan CPI: Measure, Periods & Comparison Checklist

What this reference provides

Official monthly and historical CPI resources, with separate national and Tokyo coverage and explicit base-revision documentation.

Measure and geography

Use the national series for a national question and inspect the published definition. Tokyo-area and national observations are separate geographic measures.

Period basis

The official English page documents the 2025-base revision and links monthly, annual and historical results. Base revisions require care when joining downloaded tables.

Boundaries

Do not divide an index on one base by a later index on a different base without an official compatible historical link or rebasing method. A base change alone is not inflation.

A practical comparison task

Download a consistent historical series rather than joining isolated headlines. Check geography, base, frequency and any revision notes before calculating an endpoint ratio.

Keep the interpretation with the result

An index value of 100 has meaning within its stated reference base. It does not mean the same absolute basket cost as 100 in another country. Our currency-labelled scenario can illustrate an entered yen amount with a chosen rate, but it does not claim to contain Japanese CPI or a yen exchange-rate forecast.

Primary source

Statistics Bureau of Japan CPI sources and base revisions — checked 17 October 2026. This page does not claim an authenticated test or a complete catalogue of the source’s data series.