Inflation Calculator
Calculate how inflation changes the value of money over time. Enter an amount, a start and end year, and an average annual inflation rate to see the equivalent value, cumulative inflation and lost purchasing power, with a year-by-year breakdown. Works backward in time and models deflation with a negative rate.
Input
Can be earlier than the start year to look backward in time.
Average annual inflation rate. Use a negative number to model deflation.
Output
| Year | Equivalent Value | Cumulative Inflation | Purchasing Power |
|---|---|---|---|
| No data yet | |||
This models a constant average annual rate you supply — real inflation varies year to year. For historical accuracy, use a published CPI figure for your period. Estimates for information only, not financial advice.
Guides
The Inflation Calculator shows how the value of money changes over time. Enter an amount, a start year, an end year, and an average annual inflation rate, and it tells you the equivalent value at the end of the period, the total (cumulative) inflation, and how much purchasing power a single dollar retains. A year-by-year table breaks the whole span down so you can see the erosion happen one step at a time.
It is useful for salary negotiations, retirement planning, comparing historical prices, understanding "the dollar isn't what it used to be," or sanity-checking any figure quoted in old money.
How it works
The calculator compounds a constant annual rate across the years between your two dates:
equivalent value = amount × (1 + rate / 100) ^ (end year − start year)
- Equivalent value — what your amount would need to grow to just to keep the same buying power.
- Cumulative inflation — the total percentage change over the whole period, not the yearly rate.
- Purchasing power — how much one start-year dollar buys in end-year money (below 1.0 means money lost value; above 1.0 means it gained value, which happens when you look backward or use a negative rate).
For example, $1,000 in 2015 at a steady 3% inflation is worth about $1,343.92 in 2025 — a cumulative 34.39% rise, leaving each 2015 dollar with roughly 0.74 of its buying power.
How to use it
- Enter the amount of money.
- Set the start year and end year. The end year can be earlier than the start year to look backward in time.
- Enter the average annual inflation rate as a percentage. Use a negative number to model deflation.
The result and the full breakdown update instantly. You can copy the summary or download the year-by-year table as a CSV.
What rate should I use?
The tool uses a single average rate you supply, so results are only as accurate as that number. Long-run U.S. inflation has averaged roughly 3% per year, but individual years swing widely. For a precise historical figure, look up the published Consumer Price Index (CPI) change for your exact period and enter that as the rate.
FAQ
Can I calculate inflation backward in time?
Yes. Set the end year earlier than the start year. The calculator applies a negative exponent, telling you what a present-day amount was worth in the past.
What is the difference between annual and cumulative inflation?
Annual inflation is the rate for a single year. Cumulative inflation is the compounded total across the whole span — ten years at 3% is about 34% cumulative, not 30%, because each year's inflation applies on top of the last.
How do I model deflation?
Enter a negative inflation rate. Prices fall, the equivalent value drops below the original amount, and purchasing power rises above 1.0.
Is my data private?
Yes. All calculations run entirely in your browser. Nothing you enter is sent to a server or stored.