Inflation Calculator

Free inflation calculator. See how much a sum today will be worth in the future and how inflation erodes purchasing power over time using a constant annual inflation rate.

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This tool has a free JSON API. Copy a prompt or skill below to use it with ChatGPT, Claude, or any AI agent — no API key needed.

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How inflation calculator works

Inflation is the rate at which the general level of prices rises, so each unit of currency buys less over time. A constant annual inflation rate compounds the same way interest does: after t years an amount A grows to A × (1 + r)^t in nominal terms. Equivalently, the real purchasing power of a fixed sum falls by the inverse factor each year.

This calculator takes an amount, an annual inflation rate, and a number of years, and reports three things: the future value (what your money would need to grow to in nominal terms just to keep pace), the purchasing power (what today's amount will actually be worth in today's dollars after inflation), and the inflation factor. An optional discount/return rate also produces a "real value" that accounts for a competing return.

Enter the amount, the annual inflation rate as a percentage, and the years. The result assumes a constant rate — real inflation varies year to year. Use it for rough long-horizon planning, like estimating how much retirement income will be worth decades from now or comparing salaries across years.

Frequently asked questions

How is future value calculated?
Future value = amount × (1 + inflation rate)^years. With 3% inflation, $1,000 becomes $1,343.92 after 10 years — meaning you would need that much just to buy what $1,000 buys today.
What is purchasing power?
Purchasing power is what today's amount will be worth in today's dollars after inflation. At 3% over 10 years, $1,000 has a purchasing power of about $744 — it buys only 74% of what it buys now.
What is the discount/return rate for?
The optional rate produces a "real value" — the inflation-adjusted value if the money instead earned that return. It lets you compare keeping cash (eroded by inflation) against investing it.
Is the inflation rate really constant?
No — real inflation varies each year and by country. This calculator uses a single constant rate for a quick estimate. For precise historical figures, use an official CPI series such as the US Bureau of Labor Statistics CPI calculator.