Compare purchasing power
Adjust an Amount With CPI
Negative amounts can model a liability. The reverse result uses this same entered amount.
Multiply the starting amount by the end index divided by the start index. The percentage change is that index ratio minus one, multiplied by 100.
Using the embedded Australian calendar-year averages, $10,000 in 2000 becomes $19,957 in 2025. The start index is 49.63 and the end index is 99.05. Calculations keep full precision until display.
Calendar-year values average four quarters in that year. Financial-year values average the quarters ending in September and December, then March and June of the following year. A quarterly value covers one quarter. Select one frequency for the whole comparison.
The RBA inflation calculator methodology explains these annual averages. This calculator derives them from the ABS Australian quarterly CPI series. It includes only complete years and does not interpolate missing periods.
Reverse the Inflation Calculation
To express an end-period amount in start-period purchasing power, multiply it by the start index divided by the end index. The reverse figure applies this calculation to your entered amount.
For illustrative indices of 100 and 125, an earlier $10,000 becomes $12,500. A later $10,000 has the purchasing power of $8,000 in the earlier period. Entering $12,500 as the later amount gives a reverse equivalent of $10,000.
You can also swap the historical start and end periods to make the headline figure run backwards. Falling prices produce a negative index change.
Future mode uses your assumed annual rate instead of historical observations. At an assumed 3% for two years, $10,000 becomes $10,609. The formula is amount multiplied by (1 + annual rate / 100) raised to the number of years.
Choose the Right Index
The embedded series measures Australian consumer prices and applies to Australian-dollar purchasing power. All values use the September 2025 reference base. The ABS explanation of re-referencing describes why index levels from different bases cannot be mixed directly.
Choose custom indices for an overseas comparison. Supply the relevant country’s published series and select its currency, such as US dollars or pounds sterling. The currency menu does not select overseas CPI data. Record the source and use two observations with the same coverage, frequency and reference base.
A house-price index measures property prices. A wage index measures wages. Consumer CPI measures household price changes, while an exchange rate compares currencies. A CPI-adjusted salary shows purchasing power, not the wage someone would earn.
Custom indices can compare property or wages when you supply the appropriate series. The result then follows that index and must be labelled accordingly. Currency conversion requires a separate exchange-rate calculation.
Australia, all-groups CPI, weighted average of eight capital cities. Decimal-currency periods from 1966. Quarterly data ends at 2026 Q2.
Use the Result in a Matter
An inflation comparison puts historic amounts on a common purchasing-power basis. Keep the original amount and its source beside the adjusted figure in your contribution schedule.
Record the chosen periods and index series with the calculation. The CSV retains both indices, the entered amount and the direction of each result. Custom and future calculations retain their supplied assumptions.
An indexed amount is not a property valuation or a legal entitlement. It does not establish who made a contribution, how an asset changed in value or what weight a court gives the evidence.
Use the initial contributions guide to identify the records supporting the original contribution before adding an inflation comparison.
An assumed constant annual rate, compounded over the entered term. The model starts at index 100. This is a scenario, not observed CPI.