UK inflation calculator

Find out what an amount of money from an earlier year is worth today, using the price indices the Office for National Statistics publishes. The calculator reads the ONS series directly and shows the two index values it uses, so you can check the sum.

Which index to use

Consumer Prices Index (CPI)

CPI is the UK's headline measure of inflation and the one the Bank of England's 2% target uses.

Retail Prices Index (RPI)

The ONS says RPI is not an accredited official statistic and does not recommend it as a measure of inflation, but it is still used for some contracts, student loans and index-linked gilts.

Long-run price index (RPI long-run series)

The ONS's long-run series joins earlier price indices to the RPI, so amounts from before 1987 can be compared with today. Older years rest on less complete price records.

Questions

How is this worked out?

The amount is multiplied by the price index for the later year and divided by the price index for the earlier year. An index is a list of price levels relative to a base year, so the ratio of two years' values is how much prices changed between them.

Why do CPI and RPI give different answers?

They cover slightly different things and are calculated with different formulas. The ONS explains the differences in its guide to the measures; RPI usually rises faster than CPI.

More: the latest CPI inflation rate · CPI inflation by year · cash terms and real terms. This tool repeats the ONS's published index values. It is not financial advice.