Calculate what a purchase will cost after inflation, what your money will still buy, and your real return after inflation.
Aktualisiert Geprüfte Beispiele: 4
At 3% inflation, what costs $1,000.00 today costs $1,343.92 in 10 years, and $1,000.00 kept as cash buys only $744.09 worth of today's goods. Earning 6% beats inflation: the real return is 2.913% a year.
| Jahr | Cost of the purchase | Buying power of the amount | Savings (nominal) | Savings (today's money) |
|---|---|---|---|---|
| 1 | $1,030.00 | $970.87 | $1,060.00 | $1,029.13 |
| 2 | $1,060.90 | $942.60 | $1,123.60 | $1,059.10 |
| 3 | $1,092.73 | $915.14 | $1,191.02 | $1,089.95 |
| 4 | $1,125.51 | $888.49 | $1,262.48 | $1,121.69 |
| 5 | $1,159.27 | $862.61 | $1,338.23 | $1,154.37 |
| 6 | $1,194.05 | $837.48 | $1,418.52 | $1,187.99 |
| 7 | $1,229.87 | $813.09 | $1,503.63 | $1,222.59 |
| 8 | $1,266.77 | $789.41 | $1,593.85 | $1,258.20 |
| 9 | $1,304.77 | $766.42 | $1,689.48 | $1,294.84 |
| 10 | $1,343.92 | $744.09 | $1,790.85 | $1,332.56 |
The exact Fisher relation; the shortcut nominal − inflation overstates the real rate slightly.
Inflation raises prices by a percentage each year, and it compounds like interest. At a steady rate π, a purchase costing A today costs A(1 + π)^n after n years, and cash held for n years buys only A ÷ (1 + π)^n of today's goods. The real return on savings follows Irving Fisher's relation: (1 + nominal rate) ÷ (1 + inflation) − 1.
With the defaults, 1,000 and 3% inflation for 10 years, the same purchase will cost 1,343.92 and cash of 1,000 will buy 744.09 of today's goods, a 25.59% loss of purchasing power. Savings earning 6% have a real return of 2.9126% a year, not 3%, and grow to 1,332.56 in today's money.
The inflation rate is held constant. Official price indices such as the US CPI-U move unevenly and differ by basket and country, so for past prices use the index values themselves, for example through the BLS CPI inflation calculator.
Prüfquelle: Python decimal: 1000·1.03^10 = 1343.9164; 1000/1.03^10 = 744.0939; 1.06/1.03 − 1 = 2.912621 %
Prüfquelle: With π = 0 the real rate equals the nominal rate; 1000·1.06^10 = 1790.8477 (Python decimal)
Prüfquelle: Python decimal: 100·0.98^5 = 90.3921; 100/0.98^5 = 110.6292; 1.01/0.98 − 1 = 3.0612 %
Prüfquelle: Python decimal: 50000·1.065^20 = 176182.2532; 1.08/1.065 − 1 = 1.40845 %
Multiply today's price by (1 + inflation rate) raised to the number of years. At 3% a year, something costing 1,000 today costs 1,000 × 1.03^10 = 1,343.92 in 10 years, a total price rise of 34.39%. At 3.4% a year it would cost 1,397.03.
Divide (1 + nominal return) by (1 + inflation) and subtract 1, the Fisher relation. Savings earning 6% while prices rise 3% have a real return of 1.06 ÷ 1.03 − 1 = 2.9126% a year. The shortcut 6% − 3% = 3% overstates it slightly, and the gap grows with higher rates.
US consumer prices (CPI-U) rose 3.4% in the 12 months to August 2026, and 2.4% excluding food and energy, according to the Bureau of Labor Statistics. The Federal Reserve's target is 2% a year, measured by the PCE price index rather than the CPI; the Bank of England and the European Central Bank also target 2%.
ln 2 ÷ ln(1 + inflation rate) years. At 2% inflation cash loses half its purchasing power in 35.0 years, at 3% in 23.4 years and at 3.4% in 20.7 years. Even at a 2% target rate, 1,000 held as cash for 10 years loses 17.97% of what it can buy.
Die Genauigkeit hängt von Ihren Eingaben und den Annahmen der Methode ab. Die Dezimalrechnung nutzt 50 signifikante Stellen, doch Schätzungen, numerische Verfahren und Quelldaten können ungenauer sein. Die angezeigte Rundung beseitigt diese Grenzen nicht. Anhand unabhängiger Quellen geprüfte Rechenbeispiele: 4. Beispielsweise wird „1,000 at 3% inflation for 10 years, savings at 6%“ anhand von Python decimal: 1000·1.03^10 = 1343.9164; 1000/1.03^10 = 744.0939; 1.06/1.03 − 1 = 2.912621 % geprüft.
U.S. Bureau of Labor Statistics — CPI inflation calculator; Fisher, I. — The Theory of Interest (1930), real vs nominal rates.
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Dieser Rechner enthält 4 Rechenbeispiele mit Ergebnissen aus unabhängigen Quellen. Sie laufen in der Testsuite und können auch hier ausgeführt werden.
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