Inflation Calculator

See what money from any year or month is worth today using official ONS CPI, CPIH and RPI or US BLS CPI-U data, and check if your pay has kept up.

Reviewed by Dany, RightSums team · Updated

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personal-finance · Daily life · UK & US

Enter an amount and two dates, and the calculator shows what that money is worth at the other date, how much prices rose in total and the average inflation rate a year. It uses the official index values downloaded from the Office for National Statistics for the UK and the Bureau of Labor Statistics for the US, and shows the two index numbers it used so you can check the sum yourself. You can pick a whole year or a single month, and compare CPI, CPIH and RPI side by side, or go back to 1800 with the ONS long run price series. A salary mode tells you whether your pay has kept up with prices since a past year, how much you would need now to stand still, and your real-terms change. A chart shows the cost of the same shopping over time and a year-by-year table lists annual inflation, with the latest month's data date shown above the result.

Accepted inputs

  • Country: UK (pounds) or US (dollars)
  • Amount, or your pay then and your pay now in salary mode
  • Start date: a year (annual average) or a year and month
  • End date: the latest month published, or any earlier year or month
  • Price index: CPI, CPIH, RPI or the long run RPI series from 1800 (UK); CPI-U (US)

Outputs

  • What the amount is worth at the other date
  • Total price change and average annual inflation rate
  • The two official index values used and the sum
  • Fall in purchasing power of cash kept over the period
  • UK: CPI, CPIH and RPI results side by side
  • Has my pay kept up: pay needed now, the gap, cash and real-terms change
  • Purchasing power chart over the period
  • Year-by-year table of annual inflation with the official ONS rates
  • Latest month of data, publication date and next release date

How to use the Inflation Calculator

  1. Choose UK or US, enter an amount, and pick the start date as a whole year or a single month. The end date defaults to the latest month published.
  2. The calculator looks up the official index for both dates: ONS CPI, CPIH or RPI for the UK, or the BLS CPI-U for the US. A whole year uses the annual average index.
  3. It multiplies your amount by the end index and divides by the start index, then works out the total price change and the compound average rate a year.
  4. In salary mode it multiplies your old pay by the same ratio to show the pay you need now to stand still, and compares that with what you earn.
  5. Below the result it shows CPI, CPIH and RPI side by side, a purchasing power chart and a year-by-year table of annual inflation, with links to each source.

Frequently asked questions

What is £100 in 2000 worth today?

£100 in 2000 is worth £197.52 in August 2026 prices on the ONS CPI, which averaged 72.7 in 2000 and was 143.6 in August 2026 (ONS, published 16 September 2026). On RPI the answer is £247.56. The calculator always uses the latest month the ONS has published.

How does the inflation calculator work it out?

It divides the price index at the end date by the index at the start date and multiplies your amount by the result. A whole year uses the ONS or BLS annual average and a month uses that month's index. Both index numbers are shown under the result so you can repeat the sum.

Should I use CPI, CPIH or RPI?

Use CPI for most purposes: it is the UK's headline measure and the one the Bank of England targets at 2%. CPIH adds owner occupiers' housing costs and Council Tax. Use RPI only for something that is itself linked to RPI, because the ONS says RPI is not a good measure of inflation.

How far back does the calculator go?

UK CPI and CPIH go back to January 1988, RPI to January 1987, and the ONS long run RPI series to 1800 for whole years and June 1947 for months. US CPI-U goes back to January 1913. Before 1997 the ONS CPI figures are estimates built by the ONS.

Has my pay kept up with inflation?

Your pay has kept up if it rose by more than prices over the same period. In salary mode, £25,000 in 2016 needs to be £35,650 in August 2026 on CPI (index 100.7 to 143.6, ONS), so a salary of £33,000 is a 7.4% real-terms cut despite a 32% cash rise.

Why is the average annual rate lower than the total divided by the years?

The average annual rate is compounded, because each year's rise builds on the year before. From 2000 to August 2026, CPI rose 97.5% in total, which is 2.64% a year on average, not 3.75%. It is worked out as the index ratio to the power of 1 divided by the years, minus 1.

Does the calculator include the US?

Yes, it covers the US with the Bureau of Labor Statistics CPI-U, not seasonally adjusted, monthly from January 1913. $100 in 2000 is worth $194.53 in August 2026 (BLS index 172.2 to 334.980). BLS published no index for October 2025, so choose another month or the 2025 annual average.

When is the data updated?

The data is updated each month after the ONS and BLS publish new figures. The ONS releases consumer price inflation on a Wednesday in the middle of the month for the month before; the September 2026 figures are due on 21 October 2026. The latest month in use is shown above the result.

Sources

The rates and rules in this tool come from:

Guides that use this tool

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