Retail Price Index (RPI) in United Kingdom

The Retail Price Index (RPI) is a UK inflation measure that predates the CPI, with a different basket and methodology: it uses the arithmetic mean in several components instead of the geometric mean, which tends to give a higher reading. It is published by the ONS.

It is published monthly by the ONS within the MM23 dataset (Consumer price inflation time series), alongside the CPI and CPIH, and is usually tracked as a year-on-year change.

It remains relevant for its contractual use: it indexes inflation-linked gilts, pensions, rents and rail fares (Network Rail), but its release usually moves markets less than the CPI/CPIH.

Since 2013 the ONS has judged that it does not meet national statistics standards because of its known methodological bias (the formula effect) and recommends using the CPIH for analytical purposes.