New Zealand CPI Inflation Calculator

The Inflation Calculator uses Statistics New Zealand's Consumer Price Index ("CPI") to calculate the difference in purchasing power for an amount of money between two dates, as provided by the user. The difference between the input value and the Calculator's output value represents the effect of the inflation or deflation that has occurred over that time, as measured by the CPI. Note that the official CPI data between 1914 and 1925 is incomplete, so interpolated figures have been used to replace the missing quarterly values. Non-CPI inflation estimates for the years between 1862 and 1914 have now been added to the Calculator, but these are not official CPI figures, and should not be regarded as being of the same quality as the official CPI. However, they should provide a fairly reasonable gauge of inflation over this period. For more information on the CPI, the measurement of inflation, the figures produced by the Calculator, and the sources for the pre-1914 data, select the following link: About the Inflation Calculator. An article (PDF 78KB) in the December 2003 Reserve Bank Bulletin discusses further the functionality of the Calculator and its uses.

Prior to decimalisation on 10 July 1967, New Zealand used a system of currency made up of pounds, shillings and pence. One pound was equivalent to 20 shillings, and 12 pence made up one shilling. The Calculator presumes that if a date prior to July 1967 is selected then the denomination is pounds; if a date after that is selected the denomination is presumed to be dollars. At decimalisation, £1 = $2. Note that the Calculator only works with decimals, therefore an amount like £5.11.6 needs to be input as 5.575 (£5 + 11.5/20 shillings).

A sample view of the calculator...

The Calculator will normally output a positive inflation rate if a current value is requested of a historical value, whereas a "negative" inflation rate will normally result if a historical value is requested of a current value.

Note that the historical CPI series is available in the Income and prices section of Economic Indicators in the Statistics menu. Select A3: Historical series to download the spreadsheet.