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Inflation-Adjusted Purchasing Power Calculator

See how inflation reduces the real value of money over time and what a fixed sum will actually buy in the future.

Inputs

$
%
$

What is this fixed sum worth in today's dollars?

Results update as you type, and the address bar keeps your numbers so the link you share reopens this exact calculation.

Future equivalent of today's amount

$18,061

To match $10,000 of purchasing power today.

Detailed results
Purchasing power lost to inflation$8,061
Percent of purchasing power lost44.6%
Real value of fixed future amount (today's $)$5,537
Years until purchasing power halves23.4

What this result means

Future equivalent of today's amount: $18,061.

You'll need $18,061 in the future to match today's purchasing power — inflation erodes 44.6% of your money's real value. Your fixed future amount is worth $5,537 in today's dollars.

Purchasing Power Erosion Over Time

Year-by-year real value of today's dollar amount.

Purchasing Power Erosion Over Time. 20 rows, first 12 shown.
YearFuture Equivalent ($)Real Purchasing Power (today's $)Purchasing Power Lost (%)
1$10,300$9,7092.9%
2$10,609$9,4265.7%
3$10,927$9,1518.5%
4$11,255$8,88511.2%
5$11,593$8,62613.7%
6$11,941$8,37516.3%
7$12,299$8,13118.7%
8$12,668$7,89421.1%
9$13,048$7,66423.4%
10$13,439$7,44125.6%
11$13,842$7,22427.8%
12$14,258$7,01429.9%

How this is calculated

Future equivalent = present × (1 + inflation)^years. Real value = future_amount / (1 + inflation)^years. Years to halve = ln(2) / ln(1 + inflation).

Inflation is the gradual increase in the general price level of goods and services. As prices rise, each dollar buys less — this loss of purchasing power is one of the most important forces in personal finance.

The rule of 72. Divide 72 by the inflation rate to estimate how many years it takes to halve purchasing power. At 3% inflation, your money loses half its purchasing power in roughly 24 years.

Why it matters for retirement. A $50,000 annual budget in today's dollars requires over $90,000 per year at 3% inflation after 20 years. Retirees on fixed incomes — pensions, annuities without cost-of-living adjustments — are especially vulnerable.

Real vs. nominal returns. Investment returns are often quoted in nominal terms. The real return is what remains after subtracting inflation. A 7% nominal return with 3% inflation yields approximately 4% in real purchasing power.

CPI vs. personal inflation. The Consumer Price Index (CPI) measures average inflation across a broad basket of goods. Your personal inflation rate may differ — healthcare and housing often inflate faster than CPI, while technology costs tend to deflate.

Assumptions

  • Inflation is applied at a constant annual rate (geometric compounding).
  • Purchasing power calculation uses the same rate for all goods and services.
  • Nominal figures are in current dollars; real figures converted to present-value dollars.
  • No tax effects modeled — applicable when comparing taxable investment returns against inflation.
  • Years-to-halve uses the exact logarithm formula, not the simplified Rule of 72.

Frequently asked questions

›What inflation rate should I use?

The long-run US CPI average is approximately 3%. For healthcare costs, use 5-7%. For general retirement planning, 2.5-3.5% is a common assumption. The current trailing 10-year average is a reasonable baseline.

›How does inflation affect my investments?

Equities historically outpace inflation over long periods. Bonds and savings accounts may not keep pace during high-inflation periods. Real assets (real estate, TIPS, commodities) tend to hedge inflation better than nominal bonds.

›What are TIPS?

Treasury Inflation-Protected Securities. The principal adjusts with CPI, so the real value is preserved. Yields are lower than nominal Treasuries to reflect the inflation protection. Suitable for inflation-sensitive portions of a fixed-income portfolio.

›How does inflation affect Social Security?

Social Security benefits include an annual Cost-of-Living Adjustment (COLA) tied to CPI-W, so they roughly keep pace with inflation. Private pensions and annuities without COLA riders lose real value over time.

›Is deflation better than inflation?

Mild deflation can be just as damaging as inflation. It discourages spending (why buy today if it's cheaper tomorrow?), increases real debt burdens, and can trigger deflationary spirals. Central banks target mild positive inflation (typically 2%) for this reason.

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