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Open the CPI example, inspect both index levels and follow the calculation. Prepared fields, dates and separate evidence make scope visible. We have not measured a time-saving advantage over a direct calculation.

Inspect the CPI example Sample JSON · Evidence JSON

What this example can answer

GB CPI index D7BT: December 2023 (132.2) and December 2024 (135.6), 2015=100, not seasonally adjusted. One derived year-over-year change: 2.572% displayed to three decimals; full precision is in the JSON.

This is not the separately published official headline inflation rate. It cannot rank absolute prices between countries or reconstruct publication vintages. The historical parent has 240 GB/US monthly observations, 2015–2024; that full parent is not included as a public download. No other month is answerable from this sample.

How it is calculated

100 × (135.6 / 132.2 − 1) = 2.571860816944…%. Displayed as 2.572%. This is a derived index change, not an official inflation headline.

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Prepared offline on 12 November 2026. Public hosting and remote API/MCP access are not open. These are historical snapshots, not a live feed.