onlinecalculator.me

Free inflation calculator

Enter an amount, an inflation rate, and a number of years to see the equivalent purchasing power — either in the future or back in the past.

Direction
Equivalent in future
$—
Total inflation
—%
Purchasing power loss
—%
About this calculator

How to use

  1. Choose Forward to find what today’s money is worth in the future, or Backward to find the present-day equivalent of a future or historical amount.
  2. Enter the dollar amount you want to adjust.
  3. Set the annual inflation rate — 3.1% is the US historical average; adjust for your scenario.
  4. Enter the number of years.
  5. Read the equivalent amount, total inflation percentage, and purchasing power change.

The formula

Forward (present to future):

FV = PV × (1 + r)^n

Backward (future to present):

PV = FV / (1 + r)^n

Where r = annual inflation rate as a decimal, n = years.

Purchasing power loss (forward):

loss% = (1 - 1 / (1 + r)^n) × 100

Worked example

$1,000 today at 3.1% annual inflation over 10 years:

  • Factor: (1 + 0.031)^10 ≈ 1.3579
  • Equivalent in 10 years: $1,357.90
  • Total inflation: 35.79%
  • Purchasing power loss: 26.36% (your $1,000 buys only about $736 worth of today’s goods)

Notes

  • This calculator uses a constant annual rate. Real inflation fluctuates year to year; the result is an estimate based on your chosen rate.
  • The CPI measures a broad basket of consumer goods. Specific categories (housing, healthcare, education) often inflate faster than the overall index.
  • For retirement planning, use a real return (nominal rate minus inflation) to size your portfolio in today’s dollars.

Frequently asked

How is inflation calculated?
The calculator uses the compound inflation formula: FV = PV × (1 + r)^n, where PV is the starting amount, r is the annual inflation rate as a decimal, and n is the number of years. This is the same method used by the Bureau of Labor Statistics CPI calculator.
What is the historical US inflation rate?
The long-run average US inflation rate since 1913 is approximately 3.1%, based on the Consumer Price Index (CPI) tracked by the Bureau of Labor Statistics. Recent years have seen higher rates — 2021 through 2023 averaged above 5% — so the default of 3.1% is a conservative long-run estimate rather than a current forecast.
What is the difference between forward and backward mode?
Forward mode answers: "If I have $1,000 today, what will I need in 10 years to buy the same things?" Backward mode answers: "What would $1,000 from 10 years ago be worth in today's dollars?" Both use the same formula — backward mode simply divides instead of multiplies.
How should I use this calculator in financial planning?
Use forward mode to stress-test savings and retirement projections — a 3% rate roughly halves purchasing power every 24 years. Use backward mode to put historical prices in context (for example, what did $100 in 1980 really buy?). For investment planning, subtract your expected inflation rate from your expected nominal return to find your real return.
How do I share my inflation scenario?
Press "Share with my numbers" to copy a URL that pre-fills the amount, rate, years, and direction. Anyone opening it will see your exact scenario.

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