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What is inflation?

Inflation is a measure of how prices of goods and services are changing in the UK, and it can have a big impact on people’s household finances.

Each month, the Office for National Statistics (ONS) publishes  the latest annual inflation rate, which measures the change in the price of regularly purchased items (known as the basket of goods and services) compared with the same time the previous year.

Some goods and services contribute more to the overall inflation rate than others: if some items see a large increase in prices, while others stay more stable, then inflation would be driven by the changing prices in that spending category.

So, how the headline inflation rate affects your household depends on which items you tend to spend your money on. This interactive shows how the price of different items has changed since 2018.

How to use the shopping prices comparison tool

The shopping prices comparison tool has been built to help people understand why their household might have experienced inflation. This interactive shows how the average price of different items has changed in the last year by using the published item level indices and price information we collect monthly.

You have the option to select from more than 450 items in the interactive, which are currently in the consumer prices basket used to produce inflation. These include items in a range of categories, including:

  • groceries
  • clothing and footwear
  • health
  • recreation and culture
  • services
  • transport
  • household items
  • eating and drinking out

The interactive will also show the current average price of the item compared with the same month the previous year. Details of how we have estimated average prices for each item are included in the further information section.

All the data used in the tool, from January 2018 to now, will be available through the “download all data” button.

The average prices included in the item level interactive are calculated using the price quotes collected as part of the consumer prices monthly price collection. The number of price quotes collected per item will differ and does not reflect the average of all prices possible for each item in the basket. The average price estimates presented are experimental, that is, they are still in the testing phase and are not fully developed. More information on experimental statistics is available in our guide to experimental statistics.

Please note the percentage changes in price are based on unrounded item price data so may differ from estimates based on the rounded item prices.

If you have any questions about this interactive, please email cpi@ons.gov.uk.

Further information

About the shopping prices comparison tool

Our measures of inflation are designed to reflect the change in prices of goods and services bought by all households.

The shopping prices comparison tool uses the latest available inflation indices, but it cannot predict how prices might change in the future.

The shopping prices comparison tool uses our most comprehensive measure of consumer prices inflation, which is the Consumer Prices Index including owner occupiers' housing costs (CPIH). The CPIH is very similar to the Consumer Prices Index (CPI), but includes the costs associated with owning, maintaining and living in one’s own home. It does not measure the change in the value of a house. Please note that the shopping prices comparison tool does not include any items reflecting costs associated with owning a home.

The CPIH covers household spending on goods and services but not spending by businesses.

The interactive shows price movements only of individual items in the consumer price basket. The movements of individual items might differ from the indices they feed into as weights and methods are used for the CPIH in line with international guidance.

Average prices

Average prices will be published for most items that appear in both the published item indices and price quotes. Some items have been removed because of volatile trends or the price collection method of the item. This is to ensure the average prices for items are clear and easy to understand.

Average prices are calculated by first determining an average price for the latest January. This is done by taking a weighted arithmetic mean of the price quotes collected for each item in the latest January, with a weighted mean used to reflect the relative popularity of each individual priced item. The remaining months’ average prices are calculated by multiplying the current month’s CPIH item index growth rate since January by the calculated January average price.

This method is used to avoid misleading changes in the published average price because of changes in the sample of items. However, it is important to note that the sample of prices that is collected as part of the consumer prices monthly price collection is designed to best capture price change, not price levels, which are presented in this interactive. Secondly, sample changes and quality changes over link periods might mean that average prices may not look as expected over the longer term.

Whilst the interactive will update each month with the latest inflation data, the items in the shopping prices comparison tool will be updated in March of each year to coincide with the revision of items in the inflation basket. This will cause all average prices in the interactive to be updated and revised to reflect the most recent data. The difference in average prices in the annual update will vary across items. While these estimates will be revised, the revision policy for CPIH and CPI is that they are rarely revised, and the Retail Prices Index (RPI) is never revised.

The average price methodology differs from average prices previously published in the consumer price inflation tables, which used the RPI item indices to uprate average prices. For more information on this method, please see Consumer Prices Indices Technical Manual, 2019 (Section 13.5).

The average prices in this tool will also differ from those presented in our tracking the lowest priced grocery items article, which focuses on the average price of the lowest-cost grocery items for 30 everyday items. In contrast, the average prices in this interactive are calculated using a wider distribution of prices quotes collected as part of the monthly consumer price collection.

Please note that the average price for petrol is not included in the interactive and will continue to be published in the latest monthly Consumer price inflation, UK bulletin, with no change to the methodology.

Contact

Emily Hopson
cpi@ons.gov.uk