Inflation Calculator: Future Value & Buying Power
This calculator answers two related questions about inflation: what a purchase will cost later, and what a fixed amount of money will be able to buy later. Enter an Amount, a number of Years, and an Annual Inflation Rate, and the result updates on every keystroke — no button, no signup, and nothing leaves your browser.
What This Inflation Calculator Does
The toggle at the top switches between the calculator's two modes. Future Cost projects what today's Amount will cost after the given number of Years, assuming the Annual Inflation Rate holds steady. Future Buying Power runs the same math in the opposite direction — it shows what today's Amount will still be able to buy once inflation has eaten into it. Both numbers come from the same three inputs; only the direction of the formula changes.
Future Cost: What Something Will Cost Later
In Future Cost mode, the result is Amount × (1 + Annual Inflation Rate)^Years. A $1,000 expense growing at 3% annual inflation costs about $1,343.92 in 10 years — the number below the toggle, and the "Gained" figure beneath it, is exactly that difference. This is the mode to use for planning a specific future purchase or budget line: tuition, a renovation, a large appliance, anything with a price tag today that you're pricing out for a future year — a future cost calculator with inflation built in, so you can test any rate you choose.
Future Buying Power: What Your Money Will Be Worth
Switch to Future Buying Power and the same $1,000 turns into $744.09 in today's terms after 10 years at 3% inflation — the "Lost to inflation" figure shows the $255.91 difference. This is the mode for savings, cash sitting in an account, or any fixed sum you're trying to judge honestly: the dollar amount doesn't shrink, but what it can actually purchase does, and this is that number. Think of it as a future buying power calculator — or a future spending power calculator — for cash you're not spending today.
Adding an Investment Growth Rate for Real Returns
In Future Buying Power mode, tap Investment growth to reveal the Annual Investment Growth Rate field. Set it above 0% and the calculator becomes a real rate of return calculator for inflation-adjusted comparisons — not just an investment returns calculator with inflation ignored, but one that shows what your money is actually worth after subtracting inflation's bite from your investment's nominal growth. The formula is (1 + growth rate) ÷ (1 + inflation rate) − 1 per year, not the simpler "growth minus inflation" shortcut, which is only an approximation. A 7% return against 3% inflation is a real return of about 3.88% a year — close to the naive 4% guess at these numbers, but the gap widens as either rate climbs.
How the Calculation Works
Every result on this page comes from compound growth applied once per year, for the number of years you enter — the same math behind compound interest, run forward for cost or in reverse for buying power. There's no historical Consumer Price Index data behind any of it, and there never will be: you supply the rate you want to test, whether that's a long-run historical average, your own budget's actual price increases, or a stress-test scenario, and the calculator applies it exactly, instantly, as you type — a real value of money calculator you can use for any currency or time horizon.
Frequently Asked Questions
What will $100 be worth in 20 years?
It depends entirely on the inflation rate you assume, since there's no way to know the real one in advance. At a typical long-run assumption of 3% annual inflation, $100 today has the buying power of only about $55.37 in 20 years — enter 100, 20, and 3 in Future Buying Power mode here to see it update instantly, or try your own assumed rate.
How do you calculate future value of money with inflation?
The future value formula is Amount × (1 + inflation rate)^years. That tells you what a fixed cost will grow to in future dollars — a $1,000 expense at 3% annual inflation costs about $1,343.92 in 10 years. Flip the same formula around (divide instead of multiply) to answer the opposite question: what a fixed amount of money today will be able to buy later. This calculator runs both directions from the same three numbers.
What's the difference between future cost and future buying power?
Future Cost answers "what will this specific expense cost later?" — the number goes up with inflation. Future Buying Power answers "what will this amount of money be able to buy later?" — the number goes down with inflation, because the same dollars buy less. They're the same formula run in opposite directions: multiplying by (1 + inflation)^years for cost, dividing by it for buying power.
How much will $1,000 be worth in 10 years?
At a 3% annual inflation rate, $1,000 today has the buying power of about $744.09 in 10 years — a loss of roughly $255.91 in what it can actually purchase, even though the number of dollars hasn't changed. Switch to Future Buying Power mode and enter your own amount, years, and rate to see the exact figure for your situation.
How do you calculate real rate of return after inflation?
The precise formula is (1 + nominal return) ÷ (1 + inflation rate) − 1, not the simpler "nominal minus inflation" shortcut people often use, which drifts further off the further apart the two rates are. A 7% investment return against 3% inflation works out to a real return of about 3.88% a year, not 4%. Enter both rates into the Investment Growth Rate field here and the calculator handles the compounding for you.
