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Investing & Retirement
Inflation Calculator — Future Cost & Buying Power Over Time
How rising prices erode the value of a dollar — and what your money will really be worth later
Inflation is the slow, steady rise in prices that quietly shrinks what your money can buy. A dollar today and a dollar ten years from now share a face value, but not the same purchasing power — groceries, rent, gas, tuition and a cup of coffee all cost more over time, so each future dollar stretches less far. This calculator shows both sides of that coin: how much a purchase will cost in the future and how much a dollar today will actually be worth once inflation has done its work.
The math is the same compounding engine behind savings growth, only pointed the other direction. Prices grow year after year, each year stacking on the last:
Future cost = present amount × (1 + rate)^years.
For example, $100 of spending today, at a 3% average inflation rate, will cost $134.39 in 10 years. The same dollar viewed the other way loses ground:
Future buying power = present amount ÷ (1 + rate)^years.
So $100 today has the buying power of just $74.41 in 10 years — you'd need about $34 more just to stand still.
What rate should you use? Over the long run, US inflation as measured by the Consumer Price Index (CPI) has averaged roughly 3% a year, which is the default here. Some decades run hotter (the early 1980s, and the 2021–2023 surge) and some cooler, but 3% is a reasonable planning anchor. You can override it with any average rate you like — drop in 2% if you trust the Federal Reserve's long-term target, or 4–5% to stress-test a more aggressive scenario.
This matters most for long-horizon planning. A retirement income that looks comfortable today can feel tight 25 years out: at 3%, a $50,000 annual budget needs about $104,689 to buy the same lifestyle in 25 years. A college fund, a 30-year mortgage payoff, a pension that isn't indexed, a salary that hasn't kept pace — all of them are inflation stories. Use this tool to translate today's prices into tomorrow's dollars (and back), so your savings goals, retirement targets and big-purchase plans are measured in real, apples-to-apples terms instead of nominal numbers that flatter the future.
Note: this is a planning estimate, not financial advice. Actual future prices depend on the path inflation takes, which no one can predict precisely.
📖 See also: How to Calculate a Tip (and Split the Bill)
Calculator
Fill in the fields and click "Calculate" for instant results.
📰 Formula
• Future cost = present amount × (1 + rate)^years • Future buying power = present amount ÷ (1 + rate)^years • rate = average annual inflation as a decimal (3% → 0.03) • years = number of years into the future • Total price increase % = (future cost ÷ present amount − 1) × 100
📰 Formula
• Future cost = present amount × (1 + rate)^years • Future buying power = present amount ÷ (1 + rate)^years • rate = average annual inflation as a decimal (3% → 0.03) • years = number of years into the future • Total price increase % = (future cost ÷ present amount − 1) × 100
🧪 Worked examples
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Example 2
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Example 3
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Example 4
⚠️ Common mistakes
- Using the future-cost formula when you meant buying power (one multiplies, the other divides).
- Entering the rate as 3.0 but treating it as a decimal — 3% is 0.03, not 3.0, in the math.
- Confusing nominal dollars with real (inflation-adjusted) dollars when comparing across years.
- Assuming a single average rate is exact — real inflation varies year to year.
- Forgetting that an un-indexed pension or fixed payment quietly loses value every year.
💡 Tips
- Use ~3% as a long-run US default, ~2% for the Fed's target, or 4–5% to stress-test.
- Future cost and buying power are mirror images: ×(1+rate)^n versus ÷(1+rate)^n.
- For retirement planning, inflate your annual budget out to your retirement year, then save toward that real number.
- Cash and low-yield accounts lose buying power unless their return beats the inflation rate.
- To preserve value, your investments need a return higher than inflation — that gap is your 'real' return.
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❓ Frequently asked questions
How do I calculate the future cost of something with inflation?
Multiply today's price by (1 + rate)^years. At 3% inflation, a $100 expense costs $100 × 1.03^10 = $134.39 in 10 years.
How much will $100 be worth in 10 years with inflation?
Divide by (1 + rate)^years for buying power. At 3%, $100 today buys what about $74.41 buys in 10 years — you lose roughly a quarter of its value.
What is a good average inflation rate to use?
About 3% a year matches the long-run US CPI average, so it's a solid default. Use 2% for the Federal Reserve's long-term target, or 4–5% for a more cautious estimate.
What's the difference between this and a compound interest calculator?
Compound interest grows your money forward (it adds value); an inflation calculator shows how prices erode value. The formulas mirror each other — one multiplies, the other can divide to find real purchasing power.
How much will I need in retirement after inflation?
Inflate today's annual budget to your retirement year: a $50,000 budget at 3% needs about $104,689 in 25 years to buy the same lifestyle. This is a planning estimate, not financial advice.
Does inflation reduce the value of cash savings?
Yes. Money that sits in cash or a low-yield account loses buying power every year that inflation outpaces its return. To keep up, the return has to beat the inflation rate.
How do I adjust an old price for inflation to today's dollars?
Multiply the old amount by (1 + rate) raised to the number of years that have passed. At 3%, $1,000 from 20 years ago is roughly $1,000 × 1.03^20 = $1,806 in today's dollars.
Why do prices double over time?
Because inflation compounds. By the rule of 72, prices double in about 72 ÷ rate years — roughly 24 years at 3%, or about 18 years at 4%.
Is the inflation calculator's result exact?
No. It assumes one steady average rate, but real inflation rises and falls year to year. Treat the result as a reasonable planning estimate, not a guaranteed future price.