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Purchasing Power Calculator

Use this free purchasing power calculator to see what your money will really be worth in the future. Enter an amount, the number of years ahead, and the annual inflation rate, and the tool shows its future purchasing power, how much buying power inflation takes away, and a chart of the decline year by year.

How it works

Purchasing power is what your money can actually buy. Ten thousand dollars in a drawer is still ten thousand dollars in ten years — the notes do not change — but if prices rise by 3% a year, those notes buy a quarter less than they do today. Inflation is the slow leak in every cash balance, and this calculator measures the leak: it takes an amount today, an inflation rate, and a number of years, and shows what the amount will be worth in today's buying power when the years have passed.

Each input has a clear job. The amount today is the sum you want to test — your savings, a salary, a pension, or the price of something you plan to buy later. The years into the future is how far ahead you are looking: five years to a house deposit, twenty years to retirement, or thirty years across a whole working life. The annual inflation rate is the rate at which prices rise each year. The default of 3% is the long-run average used for planning, but it is only a starting point — change it to match what you expect, and try 2% and 5% as well to see how much the answer moves. A small change in the rate makes a large difference over twenty or thirty years, which is exactly why testing a range matters.

The formula divides the amount by (1 + the inflation rate) raised to the number of years. That is the reverse of compound interest: instead of money growing, its buying power shrinks, year after year, by the same percentage. At 3% a year, $10,000 becomes $9,708.74 after one year, $9,425.96 after two, and $7,440.94 after ten — the loss is small in any single year and large across a decade. The value lost is simply today's amount minus the future purchasing power, and it is the amount of extra money you would need in the future year just to buy what you can buy today.

Read the answer as a warning and a target. The future purchasing power tells you what your money will really be worth — the figure to plan around, not the figure printed on the bank statement. The value lost is the cost of standing still: money left in a drawer, or in an account paying less than inflation, quietly loses that much buying power. If your savings earn 4% while inflation runs at 3%, your real return is only about 1%, and your purchasing power grows slowly; if your savings earn 1% while inflation runs at 3%, you are losing about 2% of buying power a year even though the balance is rising. The same logic applies to salaries and pensions: a pay rise below inflation is a pay cut in real terms.

The chart makes the long-run effect visible. The line falls slowly at first and then more steeply, because each year's loss applies to an already smaller amount — the mirror image of compound growth. At 3% inflation, $10,000 keeps about 86% of its power after 5 years, 74% after 10, 64% after 15, and 55% after 20. At 5% inflation those figures fall to 78%, 61%, 48%, and 38% — more than three-fifths of the buying power gone in twenty years. That is why long-term money needs to be invested rather than simply saved: cash protects the number, but only a return above inflation protects the buying power.

Worked example

Suppose you have $10,000 in savings and want to know what it will be worth in 10 years if inflation averages 3% a year. How much buying power will you have left?

Step 1: Work out the discount factor. (1 + 0.03)¹⁰ = 1.03¹⁰ = 1.34392. Prices will be about 34% higher in ten years at that rate.

Step 2: Divide the amount by the factor. $10,000 ÷ 1.34392 = $7,440.94. In ten years your $10,000 will buy what $7,440.94 buys today.

Step 3: Work out the value lost. $10,000 − $7,440.94 = $2,559.06 of buying power gone, even though the bank balance still reads $10,000. Enter the same figures in the calculator — amount $10,000, 10 years, inflation 3% — and it returns exactly future purchasing power $7,440.94 and value lost $2,559.06. The chart shows the same story year by year: $8,626.09 after 5 years, $6,418.62 after 15 years, and $5,536.76 after 20 years. To stand still you would need your savings to earn at least 3% a year; to get ahead, they must earn more.

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