Inflation Calculator: CPI, Purchasing Power and Rates

Inflation Calculator

Project a price with an annual inflation assumption, compare two CPI values, or calculate the annual inflation rate implied by two prices.

Use 0.5 for six months.

Inflation results

Starting amount
Equivalent ending amount
Price change
Cumulative inflation
Annualized inflation
Purchasing power retained

Inflation formulas

  • Projected future price: current price × (1 + annual inflation rate)years.
  • CPI conversion: starting amount × ending CPI ÷ starting CPI.
  • Cumulative inflation: ending value ÷ starting value − 1.
  • Annualized inflation: (ending value ÷ starting value)1 ÷ years − 1.
  • Purchasing power retained: starting value ÷ ending equivalent value.

Examples

CalculationInputsApproximate result
Project price$100, 3% annually, 10 years$134.39
Compare CPI$100, CPI 200 to 250$125 equivalent; 25% cumulative
Find annual rate$100 to $121 over 2 years10% per year
Deflation example$100, −2% annually, 3 years$94.12

Important data limitation

This calculator does not download official CPI history or forecast future inflation. Enter CPI values from the same index, geography, population group and reference base. A constant annual rate is a mathematical scenario, not a prediction. Actual prices vary by product, location and time.

Related calculators

Use the Compound Interest Calculator to compare investment growth with inflation, the Retirement Calculator for inflation-adjusted income planning, or the Percentage Calculator for general percentage change.