Free tool · Finance
Inflation Calculator
Calculate a future cost, price increase, purchasing power, and share of value kept from an amount, inflation rate, and years.
Future cost of $100 at 3% inflation for 10 years?
Prices rise $34.39; the same $100 in cash keeps 74.41% of its buying power.
- Inflation factor: (1 + 0.03)10 = ×1.3439.
- Future cost $134.39; the same cash is worth $74.41 in today's money.
How to use this inflation calculator
- Enter an amount in today's money, an annual inflation rate and the number of years.
- Read the large figure: the future cost of that amount, with the price increase and the remaining purchasing power alongside.
- There is no compounding choice to make: inflation compounds annually by definition.
What an inflation calculator is
An inflation calculator applies a constant annual inflation rate to a present amount and returns two complementary figures: what that amount will cost after the stated number of years, and what the same nominal sum of cash will be able to buy in today's dollars.
In the default case $100 today at 3% inflation for 10 years will cost $134.39 in the future — a price increase of $34.39. The same $100 held as cash will be worth only $74.41 in today's money, retaining 74.41% of its original purchasing power. The inflation factor over the term is ×1.3439.
Reading the chart
The chart under the result draws both sides of inflation across the term. The blue line is the future cost, rising as prices compound year after year. The orange line is what the same cash is worth in today's money, falling as its buying power erodes — the widening gap between the curves is the ground prices gain and cash loses. The dashed line marks the amount today. Move your mouse over the chart, or touch it, to read both values at any year.
The formulas
Future cost
Future cost = A × (1 + i)t
A is the amount today, i the annual inflation rate as a decimal and t the number of years. For the default case, $100 at 3% for 10 years produces a future cost of $134.39.
Value in today's money
Value = A ÷ (1 + i)t; share kept = (value ÷ A) × 100%
Dividing the amount by the same inflation factor shows what the cash will still buy. For the default case, $100 ÷ 1.3439 gives $74.41, so 74.41% of the value is kept.
Price increase
Price increase = future cost − A
The future cost minus the amount today: the extra money the same goods will need. For the default case, $134.39 − $100 = $34.39.
Examples
| Example | Amount today | Inflation rate | Years | Future cost | Worth in today's money |
|---|---|---|---|---|---|
| Default | $100 | 3% | 10 | $134.39 | $74.41 |
| Example 2 | $1,000 | 2.5% | 20 | $1,638.62 | $610.27 |
| Example 3 | $50,000 | 4% | 30 | $162,169.88 | $15,415.93 |
Three mistakes people make with inflation figures
Entering the rate as a decimal
The rate field takes a percentage. Type 3 for 3%, not 0.03 — entering the decimal makes the effect almost vanish.
Reading the cash value as a smaller amount of money
The $100 is still $100 on paper. What drops is what it buys: $74.41 in today's money in the default case.
Treating one rate as a forecast
The calculator applies a single inflation rate to every year. Real inflation changes from year to year, so use the result as a what-if, not a prediction.
Frequently asked questions
What does future cost mean?
It is what you would pay later for something that costs your amount today, if prices rise at the rate you entered. In the default case, a $100 purchase costs $134.39.
How are future cost and today's-money value related?
They use the same inflation factor in opposite directions. Future cost multiplies the amount by it and today's-money value divides by it. In the default case, the factor is ×1.3439.
Why is the share of value kept 74.41% in the default case?
$100 in cash divided by the factor of ×1.3439 gives $74.41. Divided by the original $100 and shown as a percentage, that is 74.41%.
Which example shows the biggest effect?
Example 3. $50,000 at 4% for 30 years has an inflation factor of ×3.2434, so the future cost is $162,169.88 and the same cash is worth $15,415.93 in today's money.
Why is there no compounding option?
Inflation compounds annually by definition, so the calculator uses annual compounding.
Does it tell me which inflation rate to use?
No. You choose the rate and the page calculates from it. It runs in your browser and is a calculation aid, not financial advice.
Privacy and important information
This calculator runs entirely in your browser: your numbers are never sent to a server, stored, or shared. It is a calculation aid, not financial advice — it does not predict actual inflation, which changes from year to year.
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