Work out consumer price index change instantly with clear inputs, formula shown and shareable results.
A consumer price index is the cost of a fixed basket expressed relative to a base year set to 100. The change in the index is the cumulative inflation since the base, and multiplying by a component's weight approximates how much of that change it contributed.
Index value
Index = Current basket cost / Base basket cost x Base index
Cumulative change
Change % = (Index / Base index - 1) x 100
Indicative estimate only. Fees, entitlements, limits and formulas vary by jurisdiction, statute, policy wording and the facts of the case. This is not legal, tax, insurance or financial advice — confirm with a qualified professional or the relevant authority.
To isolate price change from changes in what people buy. The trade-off is substitution bias, which is why baskets are periodically re-weighted.
CPI measures retail prices faced by households; wholesale or producer indices measure prices at earlier stages and exclude services.