How to Use the Cumulative Inflation Calculator
"If prices rise 3% a year, how much will they rise over 10 years?" Simply multiplying 3% × 10 years = 30% gives the wrong answer. Since prices compound on the previous year's level, the real increase is about 34.4%, not 30%. Enter the annual rate and time period, and this tool shows the exact cumulative rate and future amount.
The formula is: cumulative rate (%) = {(1 + annual rate/100)^years − 1} × 100, and future amount = current amount × (1 + annual rate/100)^years. This is useful for retirement planning, forecasting future living costs, and setting realistic savings targets that account for inflation.
Frequently Asked Questions
Cumulative rate (%) = {(1 + annual rate/100)^years − 1} × 100. You can't just multiply the annual rate by the years.
Prices rise based on the previous year's level, so the effect compounds. A 3% rate over 10 years is actually about 34.4%, not 30%.
It shows what that amount becomes after inflation over the years — how much you'd need to maintain the same purchasing power.