Inflation Calculator
Adjust money values over time using an annual inflation rate.
| # | Date | Start | Inflation | End |
|---|---|---|---|---|
| Run a calculation to see the schedule. | ||||
Use this Inflation Calculator to estimate how a fixed annual inflation rate may change the value or purchasing power of money over time. Enter an amount, inflation rate, and time period to calculate a future inflated value or reverse the calculation into today’s purchasing power.
Important: This calculator uses the constant inflation rate you enter. It does not use historical Consumer Price Index (CPI) data and should not be treated as an official historical inflation calculator.
Inflation Calculation Method
To estimate how much an amount may need to increase to maintain the same purchasing power:
Future value = Amount × (1 + inflation rate)time
Where the inflation rate is expressed as a decimal and time is measured in years.
To reverse the calculation:
Present purchasing power = Future amount ÷ (1 + inflation rate)time
Monthly Inflation Schedule
When months are included, the calculator converts the annual inflation assumption into an equivalent monthly rate:
Monthly inflation rate = (1 + annual rate)1/12 − 1
This allows partial-year periods and the month-by-month schedule to remain mathematically consistent with the entered annual rate.
Cumulative inflation over the full period is:
Cumulative inflation = [(1 + annual rate)time − 1] × 100
Worked Example
Suppose something costs $1,000 today and you assume inflation averages 3% per year for 10 years.
Future value = $1,000 × (1.03)10
Future value ≈ $1,343.92
The cumulative increase is approximately:
[(1.03)10 − 1] × 100 ≈ 34.39%
Under this constant-rate assumption, an item costing $1,000 today would need to cost about $1,343.92 in 10 years to represent the same nominal price adjustment.
Reversing the calculation:
$1,343.92 ÷ (1.03)10 ≈ $1,000
So $1,343.92 in 10 years would have approximately the same purchasing power as $1,000 today under the assumed 3% inflation rate.
Important Notes
- The entered inflation rate is assumed to remain constant throughout the entire period.
- Actual inflation changes from year to year and can be higher or lower than the rate entered.
- Different categories such as housing, food, healthcare, education, and energy can experience price changes that differ from overall inflation.
- Cumulative inflation compounds over time, so 3% annual inflation for 10 years produces more than a 30% total increase.
- The calculator estimates general purchasing-power effects and does not predict future prices.
- For historical U.S. dollar comparisons, use actual CPI data rather than an assumed constant inflation rate.