Inflation calculator 2026
Inflation is a sustained, broad rise in prices that erodes purchasing power over time, so a fixed sum of money buys progressively less the longer it goes unspent. The calculator turns a chosen amount, rate and time horizon into that sum's real value in the future and the future cost of an equivalent basket today.
- Real value then€5,536.76
- Purchasing power lost€4,463.24
- Future cost of the same basket€18,061.11
Over time
Illustration only, not financial advice. Assumes a constant rate and regular intervals; real products vary. Verify with a professional.
From a fixed sum to its shrinking buying power
The calculator applies one compounding factor to your inputs: (1 + r) raised to the power of n, where r is the annual inflation rate you set (entered as a percentage, used as a decimal) and n is the whole number of years in your horizon, rounded and capped between 1 and 100. Two figures share that same factor. The real value is the amount divided by (1 + r)^n - what your fixed sum can still buy after n years of price rises. The future cost is the amount multiplied by (1 + r)^n - what an unchanged basket priced at that amount today would cost after the same n years. Purchasing power lost is simply the amount minus the real value. Compounding happens once a year, never monthly or continuously, and every figure shown is rounded to the nearest cent.
A 10,000 EUR example over 20 years at 3 percent
Set the amount to 10,000 EUR, the rate to 3%, and the horizon to 20 years - the sliders start there by default. The calculator raises 1.03 to the power of 20, which works out to roughly 1.80611. Dividing 10,000 EUR by that factor gives a real value of 5,536.76 EUR: what your fixed sum would actually buy after two decades of 3% annual price rises. Multiplying 10,000 EUR by the same factor gives a future cost of 18,061.11 EUR: what a 10,000 EUR basket today would cost then. Purchasing power lost is 10,000 EUR minus 5,536.76 EUR, which is 4,463.24 EUR. Drag the years slider down to 10 with the rate unchanged and watch how much smaller that loss becomes.
What a single flat rate assumes away
The model assumes inflation runs at exactly the rate you enter, every single year of the horizon, with no year-to-year swings, no deflation, and no spikes. It assumes prices move in one step per year rather than gradually, and that the amount you enter just sits there - it earns no interest and no investment return of its own inside this tool. It assumes no fees, no taxes, and no currency conversion between now and the end of the horizon. It also treats the horizon as a whole number of years: a fractional value gets rounded before the formula runs. None of this is an arithmetic shortcut - it is what turning purchasing power into one adjustable number requires, rather than a real economic forecast.
Where a constant assumed rate parts ways with real prices
Real-world inflation is not a flat line: it moves with energy prices, supply shocks, wages and monetary policy, and it can swing sharply from one year to the next or run negative for a while. It also differs by what a person actually buys - a household budget of rent, food and fuel rarely tracks any single published rate exactly. The calculator has no connection to any statistics office or price index; the rate is only ever the number you typed in, held fixed for the whole period. Over a short horizon that gap barely matters, but over several decades a rate that is off by even one percentage point compounds into a real value or future cost that can sit tens of percent away from what actually happens.
Reading real value and future cost together
Treat the real value as a purchasing-power check on a fixed sum, and the future cost as the mirror question about a fixed price - both describe the same erosion from two directions, not two separate predictions. They are useful for comparing scenarios side by side: the same amount at different rates or horizons, or two horizons at the same rate, to see how fast the gap widens. They also work as a rough sanity check against other numbers, for instance whether a savings rate or a pay rise you are looking at even keeps pace with the assumed erosion. They are not a forecast of what inflation will actually do, not a recommendation about what to do with money, and not a substitute for checking real costs against real income.
FAQ
Why do real value and future cost move in opposite directions for the same input?
They come from the same compounding factor, (1 + r)^n, used two different ways. Real value divides your fixed amount by that factor, showing how much of its buying power survives. Future cost multiplies a fixed price by the same factor, showing how much more you would need to pay for an unchanged basket. Same rate, same years, same factor - just applied on opposite sides of the calculation.
Does the calculator use real inflation data, like a CPI index?
No. The rate is whatever you set on the slider - there is no live feed to any statistics office or consumer price index behind it. That single number is treated as a flat, unchanging assumption for the whole horizon. If you want the result to reflect a particular country or period, you need to supply a rate you already trust for that purpose; the tool only does the compounding arithmetic on top of it.
Can this calculator tell me if an investment beats inflation?
Only indirectly. It does not model investment growth at all - it only compounds one rate against a fixed amount to show purchasing-power erosion. To compare against a return, you would need to run that return through a separate calculation, such as a compound-interest tool, and set the two results side by side yourself; this calculator does not combine the two for you.
Why does a 2 percent versus 4 percent rate make such a big difference over decades?
Because the years sit in the exponent, not just multiplied by the rate. Doubling the rate does not double the outcome - it changes how many times the (1 + r) factor compounds on itself, and that difference grows fast over a long horizon. Two percentage points look small on a slider but can move the real-value figure by a large share of the original amount once compounded over twenty or thirty years.