Consumer Price Index: Concepts, Sources and Methods

This publication is a guide to the Australian Consumer Price Index (CPI). It outlines the major concepts, sources and methods for compiling the CPI. It also provides a historical background of the development of the CPI including the 2025 introduction of the complete Monthly CPI, and previous enhancements of the quarterly CPI. 

This is the 8th edition of the Consumer Price Index: Concepts, Sources and Methods. The chapters released in this edition have been updated to reflect changes made to the sources and methods used to compile the CPI since the 7th edition, most notably the introduction of a complete Monthly CPI.

The first edition of the Consumer Price Index: Concepts, Sources and Methods was published in 2003.

1.1 The Australian Consumer Price Index (CPI) is an important economic indicator. It measures price changes experienced by households. It is compiled according to international standards and is based on robust data collection and compilation methodologies. This publication provides a comprehensive description of price index theory and methodology, focusing on the Australian CPI and the concepts, sources and methods behind its compilation. It also provides insight into the conceptual and practical difficulties that the Australian Bureau of Statistics (ABS) encounters in compiling the CPI, and how it deals with these challenges.

1.2 The ABS  publishes a set of Frequently Asked Questions (FAQs) for those interested in a straightforward and brief account of the main features of the CPI. This Concepts, Sources and Methods publication, on the other hand, is for users who require a deeper understanding of the CPI, and of the methods and techniques used to deal with the complex situations that arise in constructing price indexes across the spectrum of household consumer expenditure. 

1.3 The CPI is compiled by the ABS each month. The CPI is released on the last Wednesday of the month following the end of the reference month, in the publication Consumer Price Index, Australia. The exception to this is the publication of the November reference period, which occurs in early January. 

1.4 Prior to the October 2025 reference month, the ABS produced the CPI on a quarterly basis. In the 2023-24 Federal Budget, the ABS was given funding to deliver a complete monthly measure of the CPI by the end of 2025. Central to the development of the complete Monthly CPI was gaining input and insights from users and data providers to ensure the Monthly CPI met the needs of government and the wider community. Consequently, the ABS undertook a public consultation process seeking feedback on the proposed design of the complete Monthly CPI:

• Design of a complete monthly Consumer Price Index – Public Consultation - Australian Bureau of Statistics - Citizen Space

The ABS published information detailing the introduction of the complete Monthly CPI in 2025:

• Complete monthly measure of the CPI

Details on the Complete Monthly CPI can be found in Chapter 3. 

1.5 The ABS continues to produce a selection of CPI series on a quarterly basis. The quarterly CPI series are compiled for quarters ending on 31 March, 30 June, 30 September, and 31 December each year. The quarterly series are updated within the CPI publication for the third month of each quarter, i.e. the releases for March, June, September and December each year. The quarterly data can be found within the data downloads section of the publication.

1.6 From October 2022 until September 2025, the ABS produced for the first time a Monthly CPI Indicator. Details on the Monthly CPI Indicator can be found in Chapter 3. The Monthly CPI Indicator was discontinued with the introduction of the Complete Monthly CPI. 

1.7 The CPI is re-weighted annually. The Household Expenditure Survey (HES) is used to update the weights in the years that it is available. For the inter-HES years, Household Final Consumption Expenditure (HFCE) data from the National Accounts is used as the principal data source for re-weighting the CPI. Prior to 2017, the CPI was reviewed and re-weighted every six years. The ABS described the change to annual re-weighting in the following information papers: 

• Information Paper: Increasing the Frequency of CPI Expenditure Class Weight Updates, July 2016
• Information Paper: An Implementation Plan to Annually Re-weight the Australian CPI, 2017

1.8 The 17th series CPI used data from the Household Expenditure Survey, Australia: Summary of Results, 2015-16 to represent household expenditure patterns. It was introduced in the December quarter 2017 following a minor review. As well as updating the weights in the CPI basket, the review included a simple examination of structures and methodologies. As part of the 17th series review, the ABS published an Information Paper:

• Information Paper: Introduction of the 17th Series Australian Consumer Price Index, 2017

1.9 Appendix 3.A contains information on series of the CPI pre-dating the 17th series.

1.10 In recognition of the interest in the extent to which the impact of price change varies across different types of households , in addition to the CPI, the ABS compiles the Selected Living Cost Indexes, Australia.

1.11 The ABS intends to update this manual periodically. Therefore, the ABS welcomes comments from users of statistics covered in this publication. You may direct your comments or questions to prices.statistics@abs.gov.au.