📉 Inflation Calculator
See what inflation does to your money — and what things will cost later.
How it works
Inflation is compound interest running against you. Prices rise by a percentage of the new, higher level every year, so the same multiplication your savings enjoy also works on the cost of everything you buy. The calculator shows you both directions of that one fact.
Going forward: future cost = amount x (1 + i)t. That is what you will need in t years to buy exactly what the amount buys today. Coming back: future worth = amount / (1 + i)t. Leave the money untouched and this is what it will feel like in today's terms. The purchasing-power loss is the gap between the two, expressed as a percentage.
A handy shortcut is the rule of 72: divide 72 by the inflation rate and you get roughly how many years it takes for prices to double — about 24 years at 3%, about 12 at 6%. US inflation has averaged close to 3% over the long run, but it refuses to arrive evenly: it touched 9% in 2022 and has been far lower in other decades. Any single rate you type in is a planning assumption, not a forecast.
An example
Take $10,000 and 3% inflation over 20 years. To buy the same basket of things in 20 years' time you will need $18,061.11 — prices have not quite doubled, but they are most of the way there.
Run it the other way and it stings more. $10,000 left sitting idle for those 20 years will buy what $5,536.76 buys today. That is a loss of 44.63% of its purchasing power, without a single dollar being spent, stolen or invested badly. Doing nothing is itself a decision — at 3% inflation it costs you nearly half your money's strength in two decades.
Common questions
Is 3% a sensible inflation rate to plan with?
It is close to the long-run US average, so it is a reasonable middle case. Cautious planners often test 4% too. Your personal inflation may differ from the headline figure — rent, school fees and healthcare have historically risen faster than the average, while electronics keep getting cheaper.
How do I stop inflation eating my money?
By earning a return above it. A savings account paying 1% while inflation runs at 3% is still losing ground, just slowly. Over long periods, diversified share investments have beaten inflation clearly, though with rough patches along the way — the real contest is return after inflation, not the headline return.
What exactly is the rule of 72?
A mental shortcut for doubling times. Divide 72 by a yearly percentage rate and you get approximately how many years it takes to double: prices at 3% inflation double in about 24 years, a debt at 18% interest doubles in about 4. It works for growth in your favour just as well as growth against you.
Related calculators
This calculator gives estimates for learning. Rates, taxes and rules change, and your lender or the IRS has the final numbers — check big decisions against the real documents.