FOI reference: FOI-2025-2883
You asked
I am writing to request information under the Freedom of Information Act 2000 regarding the composition and methodology behind the Retail Prices Index (RPI).
Please provide the following:
A complete and current list of all goods and services included in the RPI basket.
The respective weightings assigned to each item or category within the RPI calculation.
A record of all changes made to the RPI basket over the past 10 years, including additions and removals with corresponding dates.
The methodology and criteria used to determine the inclusion or exclusion of items in the RPI basket.
Confirmation of whether business costs are included in the RPI basket or excluded, and if excluded, the rationale behind this decision.
If available, I would appreciate this in an accessible spreadsheet or PDF format.
We said
Thank you for your request for information on the Retail Prices Index (RPI).
The methodology and criteria used to determine the inclusion or exclusion of items in the RPI and other inflation baskets is included in our Consumer price inflation basket of goods and services: 2025 article, describing the annual update of the basket of goods and services. A slightly more detailed version was included in our 2021 article.
Annex B of the 2025 article includes a list of the goods and services included in the current basket. The annex is available as part of the downloadable pdf of the basket article or in spreadsheet form.
The weights of the non-food-and-drink items and a fuller item description of each of them is included in the consumption segment indices spreadsheet of the microdataset that we release each month. From the February index published in March this year, the food and drink items have been combined into higher level aggregates known as "consumption segments". A description of this with links to more detailed papers is included in the data sources and quality section of our Consumer price inflation bulletin. However, the food and drink item weights for 2025 have been released as part of an answer to an ad hoc request for the data.
The descriptions of items in the published basket article and the consumption segment indices spreadsheet does not detail specific brand names. We do not include these in our publications and cannot release this under FOIA, as we believe this information would likely enable major retailers to influence the RPI by changing the price of the in-basket product and perhaps offset it with changes in price of other similar non-basket products. Therefore, we believe this disclosure would prejudice the economic interests of the UK and we are withholding this information under Section 29(1)(a) of the Freedom of Information Act 2000 (FOIA).
This exemption is subject to a public interest test. While we recognise arguments in favour of promoting accountability and transparency by public authorities for decisions taken by them, we feel this has been sufficiently accounted for by the disclosure of the rest of the guidance our price observers use. We also value the public interest in ensuring the stability of the UK economy. Should this be disrupted by challenge to current interest-rates, inflation, and economic policies, this would have a detrimental impact on a wide range of areas, impacting thousands of members of the public. We therefore believe it is in the greater public interest to withhold the requested information to prevent the potential harm caused by such disruption.
A record of the changes made to the RPI basket over the past 10 years is included in tables 2 and 3 of our Consumer prices inflation basket of goods and services articles and our Consumer Price Inflation Basket of Goods and Services: 2016 article. The tables are available as part of the downloadable pdf of the basket articles or, from 2019, in spreadsheet form.
The RPI basket is designed to measure the effect of price change on consumers, not the effect of price change on businesses. The latter is measured in the Producer Price Indices and Services Producer Price Indices. However, any changes to the cost to businesses of producing and distributing goods or services can result in changes to prices ultimately paid by consumers. In that sense, business costs can affect the RPI.