What the Inflation Impact Calculator does
This inflation calculator shows what rising prices do to money over time, at an inflation rate you choose: how much you will need in future to buy what a sum buys today, how much buying power cash loses if it sits still, and - if you enter the return your money earns - whether that return beats inflation. You can use one rate for every year or a different rate for each year.
It deliberately does not claim to know future inflation or to look up official index figures. Statistics offices such as the US Bureau of Labor Statistics publish the consumer price index; take a rate from there, from a central bank target or from your own assumption, and the page shows the consequences clearly.
How to use it
- Enter an amount in today's money and the number of years.
- Enter an annual inflation rate. For a changing path, open the yearly section and list a rate for each year; later years use the single rate.
- Optionally add the nominal return the money earns - a savings rate, for example - to see the real return after inflation.
- Read the future cost and the lost buying power, then use the table to find the figure for any year.
Reading the results
Future cost is what the same basket of goods is expected to cost after the years you chose, if prices rise at your rate. It is the amount to aim for when saving for a future expense.
Buying power of cash is the same thing seen the other way: money kept at a 0% return can buy less each year. After ten years at 3%, 10,000 buys what about 7,441 buys today.
Real return is growth after inflation, using (1 + nominal) / (1 + inflation) - 1. A savings rate below inflation is a negative real return, even though the balance keeps rising.
Worked example: 10,000 in savings over 10 years at 3% inflation
Prices rising 3% a year for 10 years multiply by 1.03^10 = 1.343916. Something costing 10,000 today costs 13,439.16 in ten years.
Kept as cash, 10,000 then buys what 10,000 / 1.343916 = 7,440.94 buys today - 25.6% of its value lost. At 3% a year, money loses half its buying power in ln 2 / ln 1.03 = 23.4 years.
If the savings earn 1.5% a year instead, the balance grows to 10,000 x 1.015^10 = 11,605.41, but the real return is 1.015 / 1.03 - 1 = -1.46% a year, and the balance is worth only 8,635.51 in today's money.
Formulas and scoring rules
- Price index after n years
index = (1 + i1) x (1 + i2) x ... x (1 + in)With one rate throughout, index = (1 + i)^n.- Future cost
future cost = amount x index- Purchasing power of cash
buying power = amount / index- Average inflation
average = index^(1/n) - 1A geometric average, not the simple mean of the yearly rates.- Real return (Fisher)
real = (1 + nominal) / (1 + inflation) - 1Shown to 2 decimals of a percent; money to 2 decimals.- Time to halve
years = ln 2 / ln(1 + average)
Which inflation rate to use
For planning, many people use their central bank's target (often around 2%) as a baseline and test a higher rate to see the risk. For looking back, use the official consumer price index for your country and period. For a specific cost - school fees, rent, healthcare - its own price history may rise faster or slower than general inflation.
The yearly list is useful after a spike: enter recent high rates for the first few years and let the calculator fall back to a long-run assumption after that.
Limitations: what the result does not prove
- It uses only the rates you enter. It is not a forecast and does not contain official CPI data.
- General inflation is an average across a basket of goods. Your own costs can rise at a very different rate.
- Taxes on interest or gains are not deducted from the nominal return.
- Deflation can be modelled with negative rates, but not below -100%.
Privacy: where your data goes
Everything you paste, type or drop is processed in this browser tab. It is not uploaded, logged, stored or sent to analytics. Session recording and tag-manager scripts are switched off on this page.
Standards and sources
- US Bureau of Labor Statistics - Consumer Price Index - checked 19 Sep 2026
- Office for National Statistics (UK) - inflation and price indices
Frequently asked questions
How much will 10,000 be worth in 10 years with inflation?
At 3% inflation, 10,000 kept as cash will buy what about 7,441 buys today, and you would need 13,439 in ten years to buy what 10,000 buys now. Change the rate to see other scenarios.
How do I calculate the future cost of something?
Multiply today's price by (1 + inflation) raised to the number of years. A 3,000 monthly cost of living grows to about 5,562 in 25 years at 2.5% inflation, so an income plan needs to allow for that.
What is a real rate of return?
It is your return after inflation. Divide one plus the nominal return by one plus inflation and subtract one. 7% nominal with 3% inflation is a 3.88% real return, slightly less than the 4% that simple subtraction suggests.
Is average inflation the same as the average of the yearly rates?
Not quite. The calculator uses the geometric average, the constant rate that produces the same total price rise. Rates of 10% and 0% average 5% arithmetically, but the geometric average is about 4.88%, because 1.1 x 1.0 = 1.0488^2.
Why does the calculator not fetch the latest CPI?
Official figures differ by country, are revised, and describe the past rather than the future. The page works with the rate you choose so that the assumption is visible and nothing is presented as live data. Check your national statistics office for published rates.
What is the rule of 70?
A shortcut: 70 divided by the inflation rate is roughly the number of years for prices to double (or money to halve in value). At 3%, that is about 23 years; the exact figure from ln 2 / ln 1.03 is 23.4 years, which the page shows.
Last reviewed by the A2Z.Tools team against the sources listed above.
