This inflation calculator answers the three questions people actually arrive
with. Pick the one you need — you do not have to fill in all of them.
Future Value. Enter an amount, an annual rate and a number of years to see what the same basket will cost later and what today's money will be worth then. This is the inflation rate future value calculator mode, and the one to use for retirement planning.
Past Value. Same three inputs, running the other way — what an amount from some years ago is worth in today's money.
Inflation Rate. Enter two figures and the tool works out the rate between them. This is how to calculate the inflation rate with CPI: put the earlier CPI in the first box and the later one in the second. It works just as well with two prices for the same product.
The result updates as you type. There is no sign-up and nothing you enter leaves your browser.
The formulas, in plain terms
All three modes come from two pieces of arithmetic. If you are trying to
calculate the inflation rate by hand, these are the ones you need:
What you want
Formula
Inflation rate between two figures
(Later − Earlier) ÷ Earlier × 100
Average rate per year
((Later ÷ Earlier)1/years − 1) × 100
Future cost of something
Amount × (1 + rate)years
What your money will be worth
Amount ÷ (1 + rate)years
The second formula is the one most people get wrong. Inflation compounds, so you cannot add
up yearly rates or divide the total by the number of years — 6% for two years is 12.36%
in total, not 12%. Over twenty years that gap becomes very large.
Working out a salary that keeps pace
An inflation rate salary calculator is the Future Value mode with your salary
as the amount. Put in what you earn now, the rate you expect, and the number of years, and the
first result is the salary you would need then to be no worse off.
It is worth doing once. At 6% inflation, a salary that stays flat for ten years has lost
about 44% of what it could buy. A raise that matches inflation is not a raise — it is
standing still.
Using CPI numbers
CPI — the Consumer Price Index — is the number statistics offices publish to track prices.
The index itself has no units; only the change between two readings means anything. To
calculate the inflation rate between 2 years, take the CPI for each year and
put them into the Inflation Rate mode.
Every country publishes its own, so use the series for the country you care about. Add the
number of years between the two readings and you also get the average annual rate, which is
the figure usually quoted in the news.
Which rate should you use?
For a forward-looking calculation there is no correct answer, because nobody knows the
future rate. What people normally do is use a long-run average for their country and then
try a higher figure to see how much it would hurt.
Run the same calculation two or three times with different rates rather than trusting one
number. The difference between 5% and 8% over twenty years is enormous, and seeing that
spread is more useful than any single answer. Rates from -50% up to 200% are accepted, so
deflation and the high-inflation years some countries have seen both work.
Why this calculator works anywhere
Inflation arithmetic is the same in every country — only the rate differs. Because you supply
the rate rather than the tool assuming one, this works for the rupee, the dollar, the pound
or anything else. Pick your currency from the list; it changes the symbol and the digit
grouping, nothing else.
It also means the tool never goes out of date. There is no built-in table of past rates to go
stale, and no year dropdown that stops at a particular year.
Frequently Asked Questions
Take the later value, subtract the earlier one, divide by the earlier one, and multiply by 100. So if a basket cost 120 then and 150 now, the inflation rate over that period is (150 − 120) ÷ 120 × 100, which is 25%. Enter both figures in the Inflation Rate mode and the tool does it for you, and if you also give it the number of years it returns the average annual rate as well.
Exactly the same way, using the CPI reading for each year in place of a price. Put the earlier CPI in the first box and the later CPI in the second. The index has no units of its own, so only the change between the two readings matters. Every country publishes its own CPI series, so use the one for the country you are interested in.
Use the Inflation Rate mode with the value or CPI for each of the two years, then add the number of years between them. You get two numbers: the total inflation across the whole period, and the average rate per year. The second one is not the first divided by the number of years, because inflation compounds.
Use the Future Value mode. Enter the amount, the rate you expect and the number of years, and you get two figures: what the same basket of goods will cost by then, and what today's amount will actually buy at that point. At 6% a year, money loses roughly 44% of its purchasing power over ten years and about 69% over twenty.
Yes. Choose Future Value and enter your current salary as the amount. The main result is the salary you would need in that many years to be exactly as well off as you are today. Anything less than that is a real-terms pay cut, even if the number on your payslip has gone up.
There is no single right answer, because future inflation is unknown. Most people use a long-run average for their own country as a starting point and then run the same calculation again at a higher rate to see the downside. Trying two or three rates tells you far more than trusting one, especially over a thirty-year horizon where small differences compound into very large ones.
Yes. The arithmetic of inflation is identical everywhere — only the rate changes from one country to another, and you supply that yourself. Choose your currency from the list to set the symbol and the digit grouping. Because no country's data is built in, the results are as valid for the pound or the dollar as they are for the rupee.
Deliberately. A built-in table of past rates would need updating every year, for every country, and would quietly go stale the moment it was not. Asking you for the rate keeps the tool correct forever and makes it work everywhere. If you want a historical figure, take the CPI readings for the two years from your national statistics office and use the Inflation Rate mode.
Yes, and it has a name — deflation. Prices fall and money buys more rather than less. The calculator accepts negative rates, so entering -2% will show costs going down and purchasing power going up. It is rare over long periods but does happen, and it is worth seeing what it does to a long-term projection.