Inflation Calculator

See how the value of money changes over time. Use the CPI mode to convert a dollar amount between two years with real U.S. inflation data, or the flat-rate modes to project an amount forward or backward at an assumed average inflation rate.

What each mode is for

Mode	You provide	It returns
CPI Data	amount, start year, end year	the equivalent amount + average inflation
Forward Flat Rate	amount, rate, years	the future value
Backward Flat Rate	amount, rate, years	the value that many years ago

Examples

$1,000 in 2000 vs 2024 (CPI)

With CPI rising from 172.2 to 313.689, $1,000 in 2000 has the same buying power as $1,821.66 in 2024 — cumulative inflation of about 82%, or roughly 2.53% per year on average.

$1,000 forward at 3% for 10 years

At an assumed 3% average inflation, you would need $1,343.92 in ten years to match the purchasing power of $1,000 today — about 34% cumulative inflation.

Formula

The CPI mode scales an amount by the ratio of the two years' Consumer Price Index values. The flat-rate modes compound (or discount) by a constant rate:

CPI mode:   value_end = value_start × CPI_end / CPI_start
Forward:    future_value = amount × (1 + rate)^years
Backward:   past_value   = amount / (1 + rate)^years

CPI data uses BLS annual averages (1982–84 = 100). For example, the index rose from 172.2 in 2000 to 313.689 in 2024; the bundled table now continues through the published 2025 annual average of 321.943.

Data source and limits

Historical mode uses annual averages for BLS CPI-U, U.S. city average, all items, series CUUR0000SA0, including the published 2025 annual average. See the BLS CPI historical tables and current CPI data. CPI-U is a broad urban-consumer index; it is not a local cost index, a personal inflation rate, an asset-price measure, or a forecast. Flat-rate modes are assumptions entered by the user.

Frequently asked questions

How does the CPI inflation calculator work?

It uses the U.S. Consumer Price Index (CPI-U) annual averages published by the Bureau of Labor Statistics. To find what an amount from one year is worth in another, it multiplies by the ratio of the two years' index values: value_end = value_start × CPI_end ÷ CPI_start.

What is the Consumer Price Index (CPI)?

The CPI measures the average change over time in the prices urban consumers pay for a representative basket of goods and services. It is the most widely used gauge of inflation, set so that the 1982–1984 average equals 100.

What is the difference between the CPI and flat-rate modes?

The CPI mode uses real, historical inflation between two years, to summarize the broad national index between those years. It does not reproduce any one household's spending or a local price change. The flat-rate modes assume a single constant inflation rate you choose — useful for projecting the future or estimating the past when you want a simple assumed rate rather than historical data.

How do I estimate future purchasing power?

Use the Forward Flat Rate mode. Enter an amount, an assumed average annual inflation rate, and the number of years. The result, amount × (1 + rate)^years, is what you would need in the future to match today's purchasing power.

Why use annual averages instead of specific months?

Annual averages smooth out seasonal and monthly noise and are the standard basis for year-to-year cost-of-living comparisons. They give a stable, representative inflation figure for each year.

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