About the inflation calculator
The inflation calculator uses price data, mostly from Stats NZ, to calculate the change in purchasing power of an amount of money between any two points in time between 1862 and the latest available figure. For example, find out how much a house worth $50,000 in 1973 is worth today or what a loaf of bread worth $4.50 today would have been worth in 1986.
The consumers price index (CPI) – published by Stats NZ – records the change in the price of a 'basket' of goods and services bought by an average New Zealand household over time. The basket is updated every three years to reflect changing trends.
More simply, the CPI tracks how the prices of everyday things that you buy change over time.
The annual inflation rate is the percentage change between the CPI price level today and one year ago. The inflation calculator allows you to calculate inflation across the entire basket of goods, or subcategories including:
- General – uses the 'all groups' CPI (Stats NZ)
- Food – Food Price Group from the CPI (Stats NZ)
- Clothing – Clothing and Footwear Group from the CPI (Stats NZ)
- Housing – House Price Index (CoreLogic)
- Wages – Hourly wage in dollars (private sector, ordinary time) from Quarterly Employment Survey (Stats NZ)
- Transport – Transport Group from CPI (Stats NZ).
For example, using the food category, you could calculate that a week’s worth of groceries that cost $250 in 2020, would have only cost around $158.43 in 2000.
Use decimals to input data
Did you know that New Zealand didn’t always use dollars and cents? Before adopting the New Zealand dollar (decimalisation) on 10 July 1967, we used pounds, shillings and pence:
- 1 pound = 20 shillings
- 1 shilling = 12 pence
- at decimalisation, £1 = $2.
The inflation calculator presumes that if a date before July 1967 is selected, then the denomination is pounds not New Zealand dollars.
It only works with decimals, therefore an amount like £5, 11 shillings, and 6 pence needs to be input as 5.575 (£5 + 11.5/20 shillings).
Data and limitations
CPI inflation and wages data are official data produced by Stats NZ and are only being reproduced in this calculator. The subcategories in the inflation calculator do not necessarily relate to CPI inflation. Refer to the 'About the inflation calculator' section above for more details.
Wages data is published by Stats NZ in the quarterly Labour Market Statistics release. The latest available wages data is sourced from the Quarterly Employment Survey (QES). See the redesign of the quarterly employment survey for information about recent changes to this survey.
While we have included estimates for the years between 1862 and 1914, these should not be seen as official data, or of the same quality as the published CPI. Also, only partial official CPI data exists between 1914 and 1925, so we have inserted interpolated figures for quarters where no official CPI value is available.
Some of the historical series used as inputs into the inflation calculator are available from our Economic Indicators statistics.
See our Prices data (M1) for historical data on the CPI, Producers Price Index (PPI), House Price Index (HPI) and Gross Domestic Product (GDP) deflator
See our Labour market data (M9) for historical data on wages
Looking at numbers – a view of New Zealand’s economic history on the NZIER website has more information on early price data
Note the inflation calculator may not give a reliable estimate of the prices of assets, such as houses, or individual goods and services where their average prices have changed significantly more or less than the change in the CPI in the specified years.
This Bulletin article discusses the calculator's functionality and gives examples of its uses and limitations:
The figures produced by the calculator are offered as guides only and should not be regarded as our ‘official’ calculations. While we have made every effort to ensure the calculations used to generate the calculator's outputs are correct, we accept no liability or responsibility for any errors or for any use to which the resulting figures may be put. The data used before 1914 does not form part of the official CPI and we make no claims as to the accuracy or reliability of these figures.