Inflation Calculator

By Bogna Haponiuk and Tibor Pal - PhD candidate.

If you have ever wondered why the same thing costs more today than it did 10 years ago, this inflation calculator will help you to answer this burning question. Read on to learn what is inflation, how to calculate the inflation rate, and how it influences your personal finances or daily life.

What is inflation

Don't worry if you don't know what inflation is, the ancient Romans didn't either! The buying power of a dollar is different today than it was twenty years ago, that is the price of goods and services changes over time. The increase in the overall level of prices is called inflation. In contrast, a persistent decline in the average price level is called deflation. These two phenomena are a prevalent feature of a capitalist economy, and they are a primary concern of economists and policymakers.

Inflation is a continuous increase in prices of goods and services. In the case of inflation, the currency gradually loses its purchasing power, so its value decreases in time, so you need more of it to buy the same amount of goods or services. Therefore, the expressions "inflation" and the "decrease in the value of money" are often used synonymously.

In general, policymakers aim to maintain stable prices; that is, keeping inflation low and constant, defined as an annual rate of close to 2%.

How to calculate the inflation rate

Since inflation can be defined as the sustained rise in the general price level and not the price level of only one or two goods, calculating the correct rate of inflation in an economy involves a carefully collected data sets and sophisticated statistical methodologies.

Wondering how to calculate inflation rate? There are several different methods; for example, the most comprehensive way is the GDP deflator, which considers the prices of all of the factors that are used in the computation of the Gross Domestic Product.

Still, one of the most common ways to measure inflation is to utilize the Consumer Price Index (CPI), which records the prices paid by consumers for a large basket of goods and services. This basket of products and services contains around 80 thousands items, representing the average cost of living. In the United States, the Bureau of Labor Statistics collects the prices through calling and visiting retail stores, service enterprises (such as cable providers, airlines, car, and truck rental agencies), rental units and medical centers across the country.

Therefore, by focusing only on a single good, we represent a simple way of calculation, where the result may differ from the official inflation rate but we hope this gives you a better understanding of the concept.

  1. Let's start with determining the time frame. Enter the start and end year into our inflation calculator. For example, you can calculate the inflation rate between 2015 and 2016.
  2. Determine the price of any product in the start year. For example, one stein of beer at last years Oktoberfest cost € 10.30.
  3. Determine the price of the same product in the end year. Our stein of Oktoberfest beer rose to € 10.60 at this years festival.
  4. Use the following formula:

inflation = (FP / IP) ^ (1/t), where

  • IP is the initial price,
  • FP is the final price,
  • t is the time elapsed (in years).
  1. You can also use our inflation calculator to find the result. In the above case, the price increase is 2.91%, which might be a proxy for the inflation rate. For a more precise calculation you may use the official CPI index in your country.

Inflation in a financial context

We don't normally keep money in a locked box. Rather, we prefer to keep our savings in bank accounts or invest them. These often have a given interest rate, which causes our savings to increase from an initial value to a future value. For example, if you have $1000 in a savings account with a 3% interest rate, you will have $1030 on your account after a year. However, this is only a nominal value which is not necessarily equal its real value.

However, it is likely that the general price level will change during the year, which will affect the real value of your money. So, even though you will have $1,030 in your account, each one of these dollars will be worth a bit less than it was a year earlier. If the inflation rate is, let's say, 2 %, then the real value of the money in your account is only $1,010. It follows that the nominal interest rate, which is offered by banks, is not the best basis for evaluating the real value of your gains. It is better to use an inflation-adjusted rate, that is, the real interest rate.

When you borrow money, though, inflation might be your friend, depending on the real interest rate. If the inflation rate is higher than the interest rate, the money you owe is less worth in real term eventually. However, when deflation happens, your debt burden might increase. In this way, deflation may redistribute money from debtors to creditors, worsening the financial position of people in debt. In economic slumps, countries often experience deflation, which is particularly harmful when plenty of people are indebted. This is what occurred after the 2008 financial crisis. In this situation, firstly stated by Irving Fisher after the Great Depression, the real values of loans increase what further hinders economic recovery.

However, as Farrell (2004) argues, deflation might be an acceptable feature of a prosperous economy if it is relatively mild and caused by supply factors. The broad expansion of Internet usage and globalization allows suppliers to continually reduce their costs and consumers to find the lowest price, implying a constant downward pressure on prices.


Now that we have seen how deflation can disrupt an economy, let's consider a situation when the overall price levels rise at an extremely high rate. This phenomenon is called hyperinflation, and, according to Cagan (1956), the first to propose a formal definition, it occurs when prices increases by 50% or more in a month.

One of the most famous and severe examples of hyperinflation was in 1920s Germany, where the Papiermark (the German currency at the time) became so worthless that kids were playing with the blocks of banknotes.

Nevertheless, Hungary had the highest monthly inflation rate ever documented, coming in at 4.19 * 1016 % in July 1946, which means that prices were doubling roughly every 15 hours and reached a whopping 207 percent daily inflation rate.

The Hungarian currency, the pengő, lost so much of its value in such a short time, that the bilpengő (one trillion pengő) note was issued to alleviate calculations. Before the new currency, the forint, was introduced, even the 100 million bilpengő note was effectively worthless.

There are several reasons why hyperinflation has such a devastating impact on an economy. People will tend to hoard goods because of rising prices, even those they don't need, which in turn can cause empty shelves in shops. Money in saving accounts vanishes, crushing consumers net worth. Also, because people aren't depositing their money, banks and lenders may go to bankruptcy. Governments fail to provide public services since tax revenues, for example sales tax or value-added tax, also plunge. Printing more money becomes the only choice, making the hyperinflation even worse.

Hyperinflation is not only a feature of the distant history: Zimbabwe experienced extreme inflation as well, peaking in November 2008 when prices doubled daily on average.

Source: Hanke, S. H., and Krus, N. (2013). World hyperinflations. In R. E. Parker and R. Whaples (Eds.), The handbook of major events in economic history. London: Routledge.

Bogna Haponiuk and Tibor Pal - PhD candidate.

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