Inflation Calculator
See how a constant annual inflation rate changes the future cost of something that costs a given amount today, and what that same amount would have been worth that many years ago.
Inflation Calculator tool
About the Inflation Calculator
This is not a Consumer Price Index lookup. Official CPI series vary by year and by basket. A single rate is still useful for back-of-the-envelope planning next to a retirement or investment projection.
Negative rates (deflation) are allowed down to just above −100%. The tool rejects a −100% rate because the factor would be zero. Pair a 7% investment return with a 3% inflation rate if you want a rough real-return sketch: the gap is what purchasing power might grow, not a forecast of either series.
How the Inflation Calculator works
A constant rate compounds like interest. Future cost multiplies; past purchasing power divides.
Future cost = amount × (1 + rate ÷ 100)^years
Past equivalent = amount ÷ (1 + rate ÷ 100)^years
Example
$1,000 at 3% for 10 years has a future cost of $1,343.92. The past equivalent — what $1,000 today would have been worth 10 years earlier at 3% — is $744.09.
How to Use the Inflation Calculator
- Enter today’s dollar amount.
- Enter an annual inflation rate.
- Enter the number of years.
- Read the future cost and the past equivalent.
- Compare the multiplier with a 2–3% planning rate if you want a typical US long-run sketch.
Inflation Calculator Examples
College-cost sketch
$20,000 of today’s tuition at 5% for 18 years is about $48,132.
2% target
Central-bank 2% goals are not a promise. At 2% for 20 years the multiplier is about 1.486.
Deflation
At −1% for 5 years, future cost is lower than today’s amount.
How to Calculate Inflation
Raise one plus the decimal rate to the number of years. Multiply today’s price for the future cost. Divide for the past equivalent.
Multipliers at 3%
These match the calculator’s constant-rate model.
| Years | Multiplier | $1,000 becomes |
|---|---|---|
| 5 | 1.159274 | $1,159.27 |
| 10 | 1.343916 | $1,343.92 |
| 20 | 1.806111 | $1,806.11 |
| 30 | 2.427262 | $2,427.26 |
Rule-of-70
A rough doubling time is 70 ÷ the percent rate. At 3%, about 23 years. The calculator’s exact 3% doubling time is ln(2)/ln(1.03) ≈ 23.45 years. At 2% the rule says 35 years; the exact figure is about 35.0 years. Use the exact power when a contract or a planning memo needs a dollar amount, and keep the rule-of-70 for a hallway estimate. Official CPI-U is a year-by-year index, not this single rate, so a 10-year official change will not match 3% compounded unless that was the average.
Frequently Asked Questions
Is this official CPI?
No. Enter the rate you want to assume. CPI-U history is published by BLS and is not a single constant.
Can years be a decimal?
Yes. 2.5 years uses the same power.
Does this adjust wages?
It scales any amount you type — prices, wages, or rent — at the same rate.
What about hyperinflation?
Rates up to 1,000% are accepted mathematically. They are not a forecast.
Should I pair this with retirement math?
Yes. A 7% nominal return and 3% inflation is roughly a 4% real return if you want a constant-dollar view.
Guides that use this calculator
- What Is Compound Interest? Formula and Examples
Compound interest grows a balance on a growing base. Here is the formula, a $1,000 example and how monthly deposits change the story.
- How Much Do I Need to Retire? Nest Egg and the 4% Rule
A retirement sketch is savings grown to a target age, then a 4% withdrawal test. Here is the math and what it leaves out.