Inflation Calculator
What money is worth over time at a given inflation rate.
Use a negative rate for deflation.
Cost in 10 years
- Purchasing power (today's money)
- $744.09
- Extra money needed
- $343.92
- Cumulative inflation
- 34.4%
Estimate. Shows how much money is needed later to buy what your amount buys today, at a constant annual rate.
How the inflation calculator works
This tool shows how inflation changes the buying power of money over time. Pick a direction, enter an amount, an annual inflation rate, and a number of years, and it adjusts the figure at a constant compound rate.
Everything rests on one growth factor: (1 + rate / 100) raised to the power of the number of years. In the future direction the tool multiplies your amount by that factor, which tells you how much money you will need later to buy what the amount buys today. In the past direction it divides by the same factor, which tells you what today’s amount was worth in money from earlier years. Alongside the adjusted figure it reports the equivalent purchasing power in today’s money and the cumulative inflation over the whole period.
Because the rate compounds, the effect grows faster the longer the horizon. A small annual rate that looks harmless over one year becomes a large gap over a few decades.
Worked example
Suppose you want to know how much a 1,000 expense today will cost in 25 years if prices rise 3.5 percent a year. Choose the future direction.
- Growth factor:
1.035^25 = 2.3632 - Future cost:
1000 * 2.3632 = 2,363.24
So you would need about 2,363 in 25 years to buy what 1,000 buys now, an extra 1,363 just to stand still. The cumulative inflation over the period is about 136 percent.
Flip it around: that same future 1,000, expressed in today’s money, is worth only 1000 / 2.3632 = 423.15. In other words, a fixed 1,000 of cash left untouched would lose well over half its buying power across those 25 years.
For a backward look, take a 1,000 amount today and ask what it was worth 20 years ago at 3 percent inflation. Choose the past direction: 1000 / 1.03^20 = 553.68. Today’s 1,000 had the buying power of about 554 two decades ago.
How to use it
- Enter the amount you want to adjust.
- Enter the annual inflation rate as a percent, for example 3 for 3 percent. Use a negative number for deflation.
- Set the number of years to project over. Fractional years are allowed.
- Choose the direction: future buying power for “how much will I need later,” or past value for “what was this worth back then.”
Limitations
This is an estimate, not financial or investment advice. It applies a single constant rate to one amount, so it does not capture rate changes from year to year, the different inflation rates of specific goods and services, taxes, or the returns you might earn by investing rather than holding cash. Real inflation varies over time and across spending categories. Use the result to understand the direction and rough scale of how money loses value, and rely on official price indices and a professional for decisions that depend on exact figures.
Frequently asked questions
What is the difference between future buying power and past value?
Future buying power answers a forward question: how much money will you need in a few years to buy what a set amount buys today? It grows your figure at the inflation rate. Past value answers a backward question: what is today's amount worth in money from some earlier year? It discounts your figure by the same rate. They are mirror images of one calculation, so switching direction simply flips multiply and divide.
What inflation rate should I use?
Use a long-run average that fits your situation rather than this month's headline figure. Many developed economies have averaged somewhere around 2 to 4 percent a year over long stretches, so a single rate in that band is a reasonable planning assumption. If you want a worst case, raise it; if you are modelling a low-inflation environment, lower it. The tool accepts any rate, and a negative rate models deflation, where prices fall over time.
Why does my purchasing power fall even when the rate is small?
Inflation compounds, so a modest rate still adds up over many years. At 3 percent a year, prices roughly double in about 24 years, which means a fixed sum of cash loses about half its buying power over that span. The longer the horizon, the larger the gap between the money figure and what it actually buys.
Does this account for my specific spending?
No. It applies one average rate to a single amount. Your personal inflation depends on what you buy, since rent, food, healthcare, and electronics move at very different rates. Treat the result as a general guide to how cash loses value over time, not a forecast for one particular basket of goods.
Is a negative rate the same as deflation?
Yes. Enter a negative rate to model deflation, where the general price level falls. In that case a future amount needed to match today's spending is lower than today's amount, and past money is worth more than the same number of units today. The math is identical; only the sign of the rate changes.