Inflation Calculator

Modify the values and click the Calculate button to use

Future Cost: $134.39

Starting Amount: $100.00
Inflation rate: 3%
Years: 10
Result: $134.39
Change: $34.39
Total change: 34.39%

The future cost compounds the current amount by the inflation rate for the number of years you enter.

Value over time

Future cost

Change in value each year

What this inflation calculator does

Inflation reduces the purchasing power of money over time. A basket of goods that costs $100 today will usually cost more in the future, and a sum of money in the future buys less than the same sum today. This calculator estimates either direction using an inflation rate you provide.

Use the forward mode to estimate what an amount today will need to be in the future to buy the same goods. Use the backward mode to estimate what a current amount would have bought in the past, or what a past amount is worth in today's purchasing power.

How to use this calculator

Choose Future cost to project an amount forward, or Past purchasing power to discount it backward.
Enter the starting amount.
Enter the average annual inflation rate.
Enter the number of years.
Click Calculate to see the result, the dollar change, and the cumulative percentage change.

The default example uses $100, 3% inflation, and 10 years. The future cost is $134.39; the past purchasing power of $100 is $74.41.

Inflation formulas

Future cost = Amount × (1 + Rate ÷ 100) ^ Years
Past value  = Amount ÷ (1 + Rate ÷ 100) ^ Years
Change      = Result − Amount
Total change % = (Result ÷ Amount − 1) × 100

The exponent compounds the rate once per year. At 3% for 10 years, the factor is 1.03^10, or about 1.3439. Multiplying $100 by that factor gives $134.39.

What the results mean

Future cost: the amount needed in the future to preserve the same purchasing power.
Past value: the amount that would have bought the same goods in the past, expressed in today's dollars.
Change: the dollar difference between the result and the starting amount.
Total change: the cumulative percentage change over the whole period, not the annual rate.

A positive total change means prices rose or purchasing power fell. In the backward mode, the percentage is negative because the past value is smaller than the current amount.

Assumptions and limitations

This calculator assumes a constant annual inflation rate for the entire period. Actual inflation varies by year, by region, and by spending category. It does not use the official Consumer Price Index history, does not adjust for taxes or fees, and does not model wage growth, investment returns, or changes in the composition of a household's spending.

The rate you enter is a planning assumption. A long-run average may be reasonable for a rough projection, but it will not reproduce a specific CPI series. For official historical inflation, use the Bureau of Labor Statistics CPI data.

Frequently asked questions

What is the difference between the two modes?

Future cost projects an amount forward: what will it take later to buy what the amount buys now. Past purchasing power discounts an amount backward: what would the current amount have bought earlier, or what is a past amount worth now.

Why doesn't the calculator use the CPI?

The task scope for this page uses a user-entered rate rather than a historical CPI table. Official CPI data is more precise for historical periods, but it requires a full monthly series and a base-period choice. The simplified model is easier to compare across scenarios.

What inflation rate should I use?

Use a rate that reflects your planning horizon and the prices you actually pay. A long-run average is a common starting point, but housing, health care, and education can rise faster than the overall index. Try more than one rate to see the range.

Does the result include taxes or investment returns?

No. It is a purchasing-power calculation only. Taxes, fees, and investment returns are separate. A nominal investment return above inflation can still lose purchasing power after taxes and fees.

Source

References:

Disclaimer

This calculator is for informational and educational purposes only. It is not a forecast of official inflation, tax advice, or investment advice. Actual inflation varies. Use the official CPI series or a qualified adviser when precision matters.

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