Inflation Calculator

See what an amount of money from one date is worth at another, using official consumer price index data.

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Formula and rounding
Reviewed October 8, 2026

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Official CPI dataA constant rate

Amount

Country / price index

From year

From period

To year

To period

$100.00 in 1990 (annual average) is worthExample

$256.30

in Aug 2026

Cumulative inflation: 156.30%
Average a year: 2.64%
Index from → to: 130.700 → 334.980

CPI data CPI for All Urban Consumers (CPI-U): All items in U.S. city average, not seasonally adjusted. Source: U.S. Bureau of Labor Statistics, Consumer Price Index for All Urban Consumers (CPI-U), U.S. city average, all items, not seasonally adjusted (series CUUR0000SA0). Licence: Public domain (U.S. federal government work, 17 U.S.C. §105). Data 1913-01 to 2026-08, retrieved 2026-10-07. Publisher’s series page

Price index

$100.00 in 1990 (annual average) had the same buying power as $256.30 in Aug 2026 (U.S. Bureau of Labor Statistics).

Assumptions

Uses CPI for All Urban Consumers (CPI-U): All items in U.S. city average, not seasonally adjusted (U.S. Bureau of Labor Statistics), the publisher’s own published annual averages.
Annual averages as published by BLS (period M13).
Shows the change in consumer prices on average; your own costs may have changed differently.
Latest observation: 2026-08.

This calculator needs JavaScript to recalculate. The figures shown are a worked example; the method is explained below and on the methodology page.

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Estimates for general information only — not financial, tax or legal advice. Your actual figures depend on your employer’s payroll, your full tax situation, your lender’s or bank’s terms and rules we may not model. Check official sources and speak to a qualified adviser before making decisions. Disclaimer · Report an error

How to use it

How to calculate the value of money over time with CPI

Prices change over time, so the same amount of money buys a different basket of goods in different years. An inflation calculator answers questions like “what is $100 from 1990 worth today?” or “what would £50 today have been worth in 2005?”.

This calculator uses each country’s official consumer price index (CPI), published by its national statistics office. Pick a country, enter an amount and choose two dates. You get the equivalent value, the total inflation between the dates, the average yearly rate and a chart of the index. Every result names the series and publisher it came from.

1
Choose a country and an amount
Pick the country whose prices you want to use. The currency follows the country. Then type the amount of money you want to compare.
2
Pick the two dates
Choose the “from” date and the “to” date. For monthly series you choose a month and year, for annual series just a year. The “to” date can be earlier than the “from” date.
3
Read the result and its source
You see the equivalent value, cumulative inflation in percent and the average annual rate, with a chart of the index. The data stamp below shows the series, publisher, latest observation and licence.

What this calculator does

Official consumer price index series for each listed country
Month-by-month dates where the series is monthly, yearly otherwise
Equivalent value of your amount at the second date
Cumulative inflation and average annual inflation rate
Works backward in time and handles falling prices
Chart of the price index between your two dates
Data stamp with series name, publisher, latest figure and licence

Worked example

Worked example: an index that rises from 100 to 125

Illustrative index values, not real CPI data

Say a price index stands at 100 in January 2000 and 125 in January 2010. You want to know what 100 (in that country’s currency) from January 2000 is worth in January 2010.

Value in January 2010: 100 × 125 ÷ 100 = 125.00
Cumulative inflation: 125 ÷ 100 − 1 = 25.00%
Average annual inflation: 1.25^(1/10) − 1 = 2.26% a year

Run it the other way and 100 in January 2010 is worth 100 × 100 ÷ 125 = 80.00 in January 2000 prices. With real data, the calculator does the same arithmetic using the official index values for your dates.

The method

How it’s calculated

The core formula is a ratio of two index values: value_to = amount × CPI_to ÷ CPI_from. Cumulative inflation is CPI_to ÷ CPI_from − 1. The average annual rate is (CPI_to ÷ CPI_from)^(1 ÷ years) − 1, where years is the time between the two dates.

The calculator uses each series in its own published index form, without re-basing or smoothing. Choose “Annual average” to compare whole years: the calculator uses the publisher’s own annual average where one is published (the US Bureau of Labor Statistics and the ONS publish them), and otherwise the mean of a complete calendar year. A year still in progress has no annual average. If a month was never published, choosing it shows a message explaining why, and nothing is estimated in its place. If you pick a date before a series starts or after its latest figure, you see a message saying so. It never extends a series beyond the published data. The full method is on our methodology page.

Full method, rounding and tests on the methodology page

Where the data comes from

Each country uses the consumer price index from its official statistics office, for example the US Bureau of Labor Statistics (CPI-U), the UK Office for National Statistics, Statistics Canada, the Australian Bureau of Statistics and Destatis in Germany. A country is listed only when its data may be reused, and each series carries the publisher’s attribution and licence. Statistics offices sometimes revise past figures, and the calculator uses values as published.

To learn how a CPI is built, and why measures like CPI, CPIH and HICP give different answers, read our guide on how inflation is measured.

Inflation compares money across time. To compare it across currencies, use the currency converter. To see whether savings keep pace with rising prices, the compound interest calculator shows a real, inflation-adjusted value. If you are saving for something whose price will rise, the savings goal calculator can set the target in today’s money.

Limits

Good to know

CPI tracks an average basket of household spending. Your own costs may have risen faster or slower, depending on what you buy.
Different measures give different answers. In the UK, for example, CPI, CPIH and RPI each move differently.
The result shows changes in prices, not in wages or asset values. Comparing incomes across decades needs a different measure.
Dates outside the published series are not estimated. The calculator shows a message instead.

Privacy

What happens to the numbers you type

Your numbers stay in your browser. MoneyOtter works out your results on your device. We don’t send the amounts you type to our servers or store them. If you allow analytics, we record only broad ranges (for example “middle tax band”) to understand how the calculators are used. Like any website with ads, this page also loads advertising scripts; see our Privacy Policy.

The calculator is plain code running in this tab. It makes no network requests with your figures, and nothing is saved when you leave unless you choose to keep it. Read the privacy policy for how ads and analytics work on this site.

Keep going

Related calculators and guides

How inflation is measured: consumer price indexes explainedThe basket, the weights, the index and the headline rate, country by country.

FAQ

Questions people ask

How do you calculate the value of money from a past year today?

Multiply the amount by the latest index value and divide by the index value for the past date: amount × CPI_to ÷ CPI_from. The calculator looks up both values from the official series.

What is CPI?

The consumer price index measures the average change in prices of a fixed basket of goods and services bought by households. National statistics offices publish it, usually each month.

Why is my personal inflation different from the official rate?

CPI uses average spending patterns. If more of your budget goes on items whose prices rose quickly, such as rent, energy or food, your personal rate will be higher than the headline figure.

What is the difference between CPI and CPIH in the UK?

CPIH adds owner occupiers’ housing costs and Council Tax to CPI. The ONS treats CPIH as its lead measure, while CPI is used for the Bank of England’s inflation target. They can give slightly different results.

Can I calculate inflation going backward in time?

Yes. Set the “to” date earlier than the “from” date. The calculator divides by the later index value, showing what today’s money would have been worth in the past.

Why do the figures sometimes change after I check them again?

Statistics offices add a new value each month or quarter and occasionally revise past data. The data stamp shows the latest observation and when the series was retrieved.

Why is there no US figure for October 2025?

The Bureau of Labor Statistics could not collect October 2025 prices during the federal government shutdown, and it cannot collect them retroactively, so no October 2025 index exists. BLS calculated the 2025 annual average (321.943) from the 11 months it did publish. The calculator uses that published average and says so; it never fills in October with an estimate.

Can I see inflation for future years?

Not from official data, because nobody publishes future CPI. The calculator does not extrapolate. To illustrate a constant rate, the inflation setting in the compound interest calculator shows its effect.

Sources

Sources and review

Page reviewed October 8, 2026 by the MoneyOtter team · Methodology · Changelog · Report an error