# Pre-Decimal Inflation Calculator

This tool calculates the change in cost of purchasing a representative ‘basket of goods and services’ over a period of time. For example, it may show that items costing £10 in 1955 cost $174.14 in 1990.

Values are denominated in dollars for periods from March quarter 1966 and in pounds (£) for preceding periods. For periods after 1965, use our decimal inflation calculator.

## Disclaimer

The results produced by the Inflation Calculator are intended as guides only and should not be regarded as 'official' Reserve Bank calculations. While every effort has been made by the Bank to ensure that the data and formulae used to generate the results are accurate, the Bank accepts no liability or responsibility for the accuracy or completeness of the resulting calculations and recommends that users exercise their own care and judgment with respect to the Inflation Calculator's use.

## Notes

### Decimalisation

The Australian currency was decimalised on 14 February 1966. Prior to decimalisation, currency was in the form of pounds, shillings and pence. One pound was equal to 20 shillings, one shilling was equal to 12 pence, and so one pound was equal to 240 pence. Also, one guinea was equivalent to 21 shillings. For details of the precise conversion of pence to cents please refer to the Australian Bureau of Statistics 1965, 'Special Article - Decimal Currency', Year Book of the Commonwealth of Australia, cat no 1301.0.

### Data Sources

Data have been compiled from various sources to produce a single long-running series that is representative of changes in consumer prices in Australia over time. From the September quarter 1948 onwards, the series used is based on the Consumer Price Index (CPI) published by the Australian Bureau of Statistics (ABS). Prior to this, a variety of different retail price indices constructed by the Australian Statistician have been used. From 1901 until the commencement of the CPI in 1948, the calendar and financial year data are from the ABS 1995 Year Book Australia. The quarterly data are available from the June quarter 1922 and are from various issues of The Labour Report. The calendar year, financial year and quarterly data from 1922 to 1948 are not strictly comparable. Further details are as follows:

- From 1901 to 1914, the Australian Statistician's 'A Series' Retail Price Index (RPI) is used, which provides the weighted average of the RPI for six State capital cities.
- From 1914 to June quarter 1948, the Australian Statistician's 'C Series' RPI is used. This series is equivalent in coverage to the 'A Series' RPI but broader in scope insofar as it records the prices of a wider range of goods. Consumption weights for this series were not updated after 1936. Also, for calendar and financial year data from the September quarter 1946 to the June quarter 1948, the 'C Series' RPI is used but with its rents component replaced by the housing group of the CPI.
- From the September quarter 1948 onwards, the ‘Quarterly’ calculator uses the CPI published by the ABS. From 1949 onwards, the ‘Calendar Year’ calculator uses an annual index, where the level of the annual index is the arithmetic average of the CPI in the four quarters of the calendar year. Similarly, the ‘Financial Year’ calculator uses an annual index, where the level of the annual index is the arithmetic average of the CPI in the last two quarters of the previous calendar year and the first two quarters of the current calendar year. The CPI was introduced in 1960 and compiled retrospectively.

For further background information see:

- Australian Bureau of Statistics 1965, 'Special Article - Decimal Currency', Year Book of the Commonwealth of Australia, cat no. 1301.0.
- Australian Bureau of Statistics 1995, ‘History of Retail Price Indexes’, Year Book Australia, cat no. 1301.0.
- Australian Bureau of Statistics 2011, Australian Consumer Price Index: Concepts, Sources and Methods, cat. no. 6461.0.
- Commonwealth Bureau of Census and Statistics, The Labour Report, various issues.

### Timing of Updates

The ‘Calendar Year’ inflation calculator is updated on the day after each December quarter CPI release. The ‘Financial Year’ inflation calculator is updated on the day after each June quarter CPI release. The ‘Quarterly’ inflation calculator is updated on the day after each CPI release. The expected release dates of ABS data are shown on the ABS Release Calendar.

### Calculation

Calendar Year: A basket of goods and services valued at $100 in calendar year 2000, would in calendar year 2015 cost $150.6.

$\mathrm{I}\mathrm{n}\mathrm{f}\mathrm{l}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{b}\mathrm{e}\mathrm{t}\mathrm{w}\mathrm{e}\mathrm{e}\mathrm{n}\mathrm{c}\mathrm{a}\mathrm{l}\mathrm{e}\mathrm{n}\mathrm{d}\mathrm{a}\mathrm{r}\mathrm{y}\mathrm{e}\mathrm{a}\mathrm{r}2000\mathrm{a}\mathrm{n}\mathrm{d}2015\phantom{\rule{0ex}{0ex}}=\left(\frac{AverageofCPIlevelinMa{r}_{2015},Ju{n}_{2015},Se{p}_{2015},De{c}_{2015}}{AverageofCPIlevelinMa{r}_{2000},Ju{n}_{2000},Se{p}_{2000},De{c}_{2000}}-1\right)\times 100\%\phantom{\rule{0ex}{0ex}}=\left(\frac{\frac{1}{4}\left(106.8+107.5+108.0+108.4\right)}{\frac{1}{4}\left(69.7+70.2+72.9+73.1\right)}-1\right)\times 100\%=50.6\%$Financial Year: A basket of goods and services valued at $100 in financial year 2000/01, would in financial year 2015/16 cost $147.1.

$\mathrm{I}\mathrm{n}\mathrm{f}\mathrm{l}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{b}\mathrm{e}\mathrm{t}\mathrm{w}\mathrm{e}\mathrm{e}\mathrm{n}\mathrm{f}\mathrm{i}\mathrm{n}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{i}\mathrm{a}\mathrm{l}\mathrm{y}\mathrm{e}\mathrm{a}\mathrm{r}2000/01\mathrm{a}\mathrm{n}\mathrm{d}2015/16\phantom{\rule{0ex}{0ex}}=\left(\frac{AverageofCPIlevelinSe{p}_{2015},De{c}_{2015},Ma{r}_{2016},Ju{n}_{2016}}{AverageofCPIlevelinSe{p}_{2000},De{c}_{2000},Ma{r}_{2001},Ju{n}_{2001}}-1\right)\times 100\%\phantom{\rule{0ex}{0ex}}=\left(\frac{\frac{1}{4}\left(108.0+108.4+108.2+108.6\right)}{\frac{1}{4}\left(72.9+73.1+73.9+74.5\right)}-1\right)\times 100\%=47.1\%$Quarterly: A basket of goods and services valued at $100 in March 2000, would in December 2015 cost $155.5.

$\mathrm{I}\mathrm{n}\mathrm{f}\mathrm{l}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{b}\mathrm{e}\mathrm{t}\mathrm{w}\mathrm{e}\mathrm{e}\mathrm{n}\mathrm{M}\mathrm{a}\mathrm{r}\mathrm{c}\mathrm{h}2000\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{D}\mathrm{e}\mathrm{c}\mathrm{e}\mathrm{m}\mathrm{b}\mathrm{e}\mathrm{r}2015\phantom{\rule{0ex}{0ex}}=\left(\frac{CPIlevelinDe{c}_{2015}}{CPIlevelinMa{r}_{2000}}-1\right)\times 100\%=\left(\frac{108.4}{69.7}-1\right)\times 100\%=55.5\%$