💸 Inflation Calculator: Future Cost and Purchasing Power
By Shihab Mia · Updated 2026-07-04
This inflation calculator gives an estimate based on a single constant rate you assume for the whole period. Real inflation varies year to year, so the result is a projection, not financial advice or a guarantee.
Please enter a valid amount, rate and a number of years of 0 or more.
-
-
This inflation calculator shows how a set amount of money changes in value over time at an assumed annual inflation rate. Enter an amount, a rate and a number of years, and it returns the future cost of the same basket of goods, the future purchasing power of that money in today terms, and the cumulative inflation across the whole period. In short, at 3 percent inflation, 1,000 dollars today costs about 1,343.92 dollars in 10 years, while that same 1,000 dollars will buy only about 744.09 dollars worth of goods.
What is the Inflation Calculator?
Inflation is the steady rise in the general price level, which means each unit of currency buys a little less as time passes. An inflation calculator turns that abstract idea into two concrete numbers. The first is the future cost of a basket of goods: what you would have to pay later to buy exactly what a given amount buys today. The second is future purchasing power: what today money will actually be worth once prices have risen. These are mirror images of the same effect, and seeing both is why an inflation calculator is more useful than a single headline figure.
The method is compound growth applied to prices. To find future cost, the inflation calculator multiplies your amount by (1 + rate/100) raised to the number of years, so a constant rate compounds year on year just like interest. To find purchasing power, it divides by the same factor instead, discounting today money back to what it will be worth. Cumulative inflation is simply how much prices rise in total over the period, expressed as a percentage, and it is almost always larger than the annual rate because each year builds on the last.
Why does the gap between cost and purchasing power matter so much over long horizons? Because compounding is relentless. A modest 3 percent inflation rate roughly doubles prices in about 24 years, which is why a salary or a savings pot that looks comfortable now can feel thin decades later. Retirement planning, long term savings goals and any fixed income stream all need an inflation calculator to stay honest about future value. Ignoring inflation is one of the most common ways people overestimate how far their money will stretch.
A key caveat: this inflation calculator assumes one constant rate, which never happens in the real world. Actual inflation is measured after the fact by agencies such as the US Bureau of Labor Statistics through the Consumer Price Index (CPI), and it swings with energy prices, wages, supply shocks and policy. Use this tool to model scenarios and compare assumptions, not to predict an exact future number. Running it at a low, a moderate and a high rate gives you a realistic range rather than a single false-precision answer.
When to use it
- Checking whether a long term savings goal will still cover its purpose once inflation has eroded the money.
- Estimating how much a salary needs to rise each year just to keep the same purchasing power.
- Seeing what a fixed pension or annuity payment will really be worth 10, 20 or 30 years from now.
- Comparing prices across time, for example what an item that cost a set amount years ago would cost today.
- Stress testing a retirement plan by running low, moderate and high inflation scenarios side by side.
- Explaining to students or clients why cash held under the mattress loses value even though the number stays the same.
How to use the Inflation Calculator
- Enter the amount of money you want to test, in today dollars.
- Enter the annual inflation rate you want to assume, as a percentage.
- Enter the number of years to project forward.
- Read the future cost, the future purchasing power and the cumulative inflation, updated instantly.
- Use the Copy result button to save the full breakdown, and try a few different rates to see a realistic range.
Formula & method
Worked examples
You want to know what 1,000 dollars today will cost, and be worth, in 10 years at a steady 3 percent inflation rate.
- Convert the rate to a factor per year: 1 + 3/100 = 1.03
- Raise it to the number of years: 1.03 to the power of 10 = 1.343916
- Future cost = 1,000 x 1.343916 = 1,343.92
- Future purchasing power = 1,000 / 1.343916 = 744.09
- Cumulative inflation = (1.343916 - 1) x 100 = 34.39 percent
Result: Future cost about 1,343.92 dollars, purchasing power about 744.09 dollars, cumulative inflation 34.39 percent.
You are planning a retirement and want to know what a 50,000 dollar yearly budget will need to be in 20 years at 4 percent inflation.
- Yearly factor: 1 + 4/100 = 1.04
- Compound over 20 years: 1.04 to the power of 20 = 2.191123
- Future cost = 50,000 x 2.191123 = 109,556.16
- Future purchasing power = 50,000 / 2.191123 = 22,819.35
- Cumulative inflation = (2.191123 - 1) x 100 = 119.11 percent
Result: You would need about 109,556 dollars in 20 years to match a 50,000 dollar budget today, and 50,000 dollars then buys about 22,819 dollars worth now.
What 1,000 dollars today grows to in cost at different inflation rates and horizons
| Years | 2% rate | 3% rate | 5% rate | 7% rate |
|---|---|---|---|---|
| 5 years | 1,104.08 | 1,159.27 | 1,276.28 | 1,402.55 |
| 10 years | 1,218.99 | 1,343.92 | 1,628.89 | 1,967.15 |
| 20 years | 1,485.95 | 1,806.11 | 2,653.30 | 3,869.68 |
| 30 years | 1,811.36 | 2,427.26 | 4,321.94 | 7,612.26 |
Approximate years for prices to double at a constant inflation rate (rule of 72)
| Inflation rate | Years to double prices |
|---|---|
| 2% | about 36 years |
| 3% | about 24 years |
| 4% | about 18 years |
| 5% | about 14 years |
| 7% | about 10 years |
| 10% | about 7 years |
Common mistakes to avoid
- Confusing future cost with lost purchasing power. These are two different figures. Future cost is what the same basket will cost later (a bigger number), while purchasing power is what today money will be worth later (a smaller number). Reading only one of them hides half the story of what inflation does.
- Assuming cumulative inflation equals the annual rate times the years. Inflation compounds, so 3 percent for 10 years is not 30 percent, it is about 34.4 percent. Adding the annual rate up linearly always understates how much prices actually rise over a long period.
- Treating one assumed rate as a prediction. This inflation calculator uses a single constant rate you choose, but real inflation moves every year. Use the tool to model a range of scenarios, not to forecast an exact future number.
- Forgetting that investment returns can offset inflation. Money left as idle cash loses purchasing power at the full inflation rate. Money that earns interest or investment returns only loses ground to the extent inflation outpaces those returns, which is the real rate of return.
Glossary
- Inflation
- The general rise in prices over time, which reduces how much each unit of money can buy.
- Inflation rate
- The percentage increase in the general price level over a period, usually quoted per year.
- Purchasing power
- The quantity of goods and services a fixed amount of money can buy at a given time.
- Cumulative inflation
- The total percentage rise in prices across a whole multi year period, after compounding each year.
- Consumer Price Index (CPI)
- The official measure of average price changes for a basket of goods and services, published by the US Bureau of Labor Statistics.
- Real value
- A money amount expressed in constant purchasing power, after stripping out the effect of inflation.
Frequently asked questions
What does an inflation calculator do?
An inflation calculator shows how the value of money changes over time at an assumed inflation rate. You enter an amount, a rate and a number of years, and it returns the future cost of the same goods, the future purchasing power of that money, and the total cumulative inflation over the period.
How is future value from inflation calculated?
Future cost is the amount multiplied by (1 + rate/100) raised to the number of years, which compounds the rate each year. For example, 1,000 dollars at 3 percent for 10 years is 1,000 x 1.03 to the power of 10, which is about 1,343.92 dollars.
How do I work out purchasing power in the future?
Divide the amount by (1 + rate/100) raised to the number of years, instead of multiplying. At 3 percent inflation, 1,000 dollars in 10 years has the purchasing power of about 744.09 dollars in today money, because prices have risen while the number of dollars stayed the same.
Why is cumulative inflation higher than the annual rate?
Because inflation compounds. Each year raises prices on top of the previous year, so the increases stack multiplicatively rather than adding up. A 3 percent annual rate over 10 years produces about 34.4 percent cumulative inflation, not 30 percent.
What inflation rate should I use in the calculator?
A common long run assumption for developed economies is 2 to 3 percent, but there is no single correct figure. Check recent Consumer Price Index (CPI) data from the US Bureau of Labor Statistics for context, and run low, moderate and high rates to see a realistic range rather than one number.
Is this inflation calculator accurate for planning?
It is accurate for the math, but only as good as the constant rate you assume. Real inflation changes every year, so treat the output as an estimate and a scenario tool, not a precise forecast or personal financial advice.
Sources
- Consumer Price Index (CPI) , U.S. Bureau of Labor Statistics (2026)
- CPI Inflation Calculator , U.S. Bureau of Labor Statistics (2026)
- Inflation, explained , International Monetary Fund (IMF) (2023)