A dollar in your pocket is a melting ice cube. At 3.5 percent annual inflation, $1,000 today buys what about $708 buys in ten years -- nearly a third of its purchasing power gone without you spending a cent. Inflation never sends a bill, which is why it is the most underestimated force in personal finance. This calculator makes the erosion visible.

Enter any amount, an annual inflation rate, and a number of years. The tool compounds the rate forward to show the future equivalent -- what you will need later to buy what the money buys today -- and the purchasing power lost along the way. It also runs the math backward: hand it a future amount and it tells you what that sum is worth in today's dollars, the figure you actually need for retirement planning.

The default 3.5 percent sits near long-run US experience, but the honest input is your personal inflation rate. Healthcare and college costs have risen near 5 percent for decades; electronics have fallen. A retiree budgeting 20 years of medical spending should test 5 percent, not 3. Run both scenarios: the gap between them is the cost of assuming average inflation applies to your life.

With the pre-filled defaults — Original Amount $1,000, Annual Inflation Rate 3.5%, Number of Years 10 — the Inflation Calculator returns Future Equivalent Amount $1,410.60, Purchasing Power Lost $410.60, Today's $ for Same Value $708.92. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.