UK RPI inflation rate

Source: Office for National Statistics (ONS), series CZBH. Monthly, usually a Wednesday in the middle of the month, 7am; published with CPI; next release 21 October 2026

UK RPI inflation rate: every value, by year, with a CSV download →

What it measures

The Retail Prices Index (RPI) is the UK's oldest measure of price change. Unlike CPI, it includes mortgage interest payments, house depreciation and council tax, and it uses a different averaging formula for some prices. The ONS describes RPI as a poor measure of inflation and it is not accredited official statistics, but it is still published because it is written into index-linked gilts, some pensions, commercial contracts and regulated prices such as some rail fares, and it is used for interest on some student loans. See RPI in the glossary.

How to read it

RPI is usually higher than CPI. The ONS attributes much of the gap to the "formula effect": RPI uses an arithmetic average (the Carli formula) for some prices, which the ONS says pushes the index upwards. Movements in mortgage interest rates also feed directly into RPI, so it can rise or fall faster than CPI when Bank Rate changes. Because the gap is persistent, a claim that compares a pay rise or benefit uprating with RPI will look different from one using CPI or CPIH for the same month. Quote the index by name and the month it covers.

Background

The ONS 12-month rate series for RPI starts in June 1948; the index itself has been published since 1947. In the ONS series the highest rate is 26.9% in August 1975 and the lowest is minus 1.6% in June 2009, when falling mortgage interest pushed RPI below zero. RPI lost its National Statistics status in 2013. In November 2020 the Chancellor and the UK Statistics Authority announced that RPI methods will be aligned with CPIH from 2030, removing the gap between the two from then on.

Why is RPI higher than CPI?

The ONS gives two main reasons. RPI averages some prices with the Carli formula, which tends to give a higher result than the formula used in CPI, and RPI includes housing costs such as mortgage interest payments that CPI leaves out. The size of the gap changes from month to month, so check both rates for the same month rather than assuming a fixed difference.

What is RPI still used for?

RPI is still written into index-linked gilts, some older pension schemes and commercial contracts, and has been used to set some regulated rail fares and the interest on some student loans. The ONS keeps publishing it for these existing uses, while recommending CPIH or CPI for measuring inflation.

What happens to RPI in 2030?

The UK Statistics Authority and the Chancellor announced in November 2020 that from 2030 the RPI will be calculated using the methods and data sources of CPIH. RPI will keep its name, but in practice its rate will then track CPIH, so the long-running gap between RPI and the other measures is expected to close.

Related questions

• What is the difference between CPI, CPIH and RPI?
• How is UK inflation measured?

More on this source: UK Statistics Authority and Office for Statistics Regulation (OSR)