HM Treasury

Economic data & tools

User's guide: Overview of GDP deflator series

This page has useful, general information on the GDP deflator series. Further information and more background detail is available on the further background page.

What is the GDP deflator?

The GDP deflator can be viewed as a measure of general inflation in the domestic economy. Inflation can be described as a measure of price changes over time. The deflator is usually expressed in terms of an index, i.e. a time series of index numbers. Percentage changes on the previous year are also shown. The GDP deflator reflects movements of hundreds of separate deflators for the individual expenditure components of GDP. These components include expenditure on such items as bread, investment in computers, imports of aircraft, and exports of consultancy services.

Uses of the GDP deflator series

The series allows for the effects of changes in price (inflation) to be removed from a time series, i.e. it allows the change in the volume of goods and services to be measured. The resultant series can be used to express a given time series or data set in real terms, i.e. by removing price changes.

Where do the figures come from?

A series for the GDP deflator in index form is produced by the Treasury from data provided by the Office for National Statistics (ONS). Forecasts are usually updated around the time of major policy announcements such as the Pre-Budget Report, and the Budget.

Rounding Convention

GDP deflators for earlier years (up to and including the most recent year for which full quarterly data have been published) are presented to three decimal places. The index for future years has been removed as the forecasts were not as accurate as this detail would suggest.

Percentage year-on-year changes are given to two decimal places for earlier years, forecast years are presented as published in the Pre-Budget Report and the Budget to the nearest quarter percent.


The GDP deflator set is updated after every ONS Quarterly National Accounts release (at the end of each quarter) and whenever Treasury updates it's forecasts (usually twice a year).


The deflator set is circulated to everyone on the Treasury's mailing list. To be placed on this list simply e-mail Anyone needing electronic copies in spreadsheet format can also e-mail this contact address.

GDP Deflators index page

Economic Data and Tools

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