Inflation calculator
Convert an amount between years with a built-in sample CPI index to see cumulative and average inflation, project future equivalent amounts and today’s purchasing power at your own inflation rate, and use the Fisher equation for the nominal return you need.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Inputs
All money is integer cents; the index is built by chaining each year’s year-on-year change onto the 2015 base of 100.
Sample data: the magnitudes follow the annual CPI published by China’s National Bureau of Statistics, kept here for demonstration and teaching only — check the official release for current figures.
Purchasing power conversion
115,314.9615,314.9615.31%1.60%2015: 100.0000002024: 115.314957Projection at your own inflation rate
Uses a fixed annual inflation rate and ignores the CPI table above.
128,008.4578,119.84Required return (Fisher equation)
The Fisher equation: (1 + nominal) = (1 + real) × (1 + inflation) — preserving purchasing power needs less than the inflation rate itself.
5.06%2.94%Sample CPI table (2015 = 100)
Sample data: the magnitudes follow the annual CPI published by China’s National Bureau of Statistics, kept here for demonstration and teaching only — check the official release for current figures.
| Year | YoY change | Index |
|---|---|---|
| 2015（Base） | — | 100.000000 |
| 2016 | 2.0% | 102.000000 |
| 2017 | 1.6% | 103.632000 |
| 2018 | 2.1% | 105.808272 |
| 2019 | 2.9% | 108.876712 |
| 2020 | 2.5% | 111.598630 |
| 2021 | 0.9% | 112.603017 |
| 2022 | 2.0% | 114.855078 |
| 2023 | 0.2% | 115.084788 |
| 2024 | 0.2% | 115.314957 |
What this tool does
- Put an old price or salary into today’s money: 100,000 from 2015 is worth about 115,314.96 in 2024 on the built-in sample index, a cumulative 15.31% of inflation.
- See how fast money loses value: at 2.5% a year, 100,000 needs to become 128,008.45 in ten years to buy the same basket — equivalently, 78,119.84 today equals 100,000 in ten years.
- Set a return target with the Fisher equation: a 3% real return with 2% inflation needs 5.06% nominal, not the 5% you get by adding.
- Get a feel for the index: the sample table lists the year-on-year change and the chained index for 2016–2024, so "about 2% a year" stops being an abstraction.
Example
Input
Amount 100,000, from 2015, to 2024
Output
Equivalent amount 115,314.96; difference 15,314.96; cumulative inflation 15.31%; average annual inflation 1.60%; from index 100; to index 115.314957
The index chains the year-on-year changes from 2016 to 2024 onto the 2015 base of 100, and the equivalent amount is 100,000 × 115.314957 / 100. The data is a sample — use the official release for real work.
Frequently asked questions
How reliable is the built-in CPI table?
It is sample data: the magnitudes follow the annual CPI published by China’s National Bureau of Statistics so the logic and scale are realistic, but it is not guaranteed to match the latest release and it has no provincial or category breakdown. For serious analysis replace the table with official figures or use the custom inflation rate.
What is the difference between cumulative and average inflation?
Cumulative inflation is the total change over the whole span (15.31% across nine years in the example) while the average is the equivalent yearly compound rate (1.60%); they are linked by (1 + average)^years = 1 + cumulative. Only the average is meaningful when comparing periods of different lengths.
Why is the nominal return not just the real return plus inflation?
Because the compounding multiplies: the Fisher equation is (1 + nominal) = (1 + real) × (1 + inflation). A 3% real return with 2% inflation needs 5.06% nominal rather than 5%, and the extra 0.06 of a percentage point is inflation eating into the return itself. The higher inflation goes, the wider that gap.
Can the inflation rate be zero, or very large?
Zero is fine — the future equivalent amount simply equals today’s. The ceiling is 100%, above which the tool rejects the input, because hyperinflation (prices doubling monthly, say) falls outside a model that assumes one rate per year and needs to be broken into shorter periods.
Can I use the result to make investment decisions?
No. It answers a mathematical question about what a sum of money is worth in different years, ignoring taxes, investment risk and the fact that your own spending mix (housing, for instance, weighs far more than it does in the CPI basket) differs from the average. Treat it as a way to understand purchasing power, not a return forecast.
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