Where does the CPI data come from?

ONS series D7BT — the official UK Consumer Prices Index (All Items), indexed to 2015 = 100. This is the same series HMRC, the Bank of England and the Treasury cite for inflation measurement. We use annual averages.

What is the difference between CPI and RPI?

CPI (D7BT) is the government's preferred measure since 2010 and is used for most state benefits and the Bank of England's inflation target. RPI (older series) is still used for some legacy indexations (rail fares, some student loans) but the ONS no longer treats it as a "national statistic". We use CPI.

Is this the same as the Bank of England inflation calculator?

Results should match to within rounding. Both use ONS D7BT annual averages. Minor differences can arise from which index point each tool uses (annual average vs a specific month).

Why can I only pick certain years?

Our dataset uses ONS annual averages. Earlier data (pre-2015) is provided at 5-year intervals; from 2015 onwards every year is covered. Sub-year granularity (monthly CPI) is possible via the ONS website directly.

Does this account for regional differences?

No — CPI D7BT is a single UK-wide index. ONS publishes regional price-level comparisons separately (Relative Regional Consumer Price Levels) but not regional inflation time series. London costs are typically 10 to 15 percent higher than the national average, which CPI does not capture directly.

UK Inflation Calculator 2026/27

Adjust any GBP amount between years using ONS CPI (series D7BT). See what £100 in 1990 is worth today or what last year's salary was worth a decade ago.

CPI-adjusted value

£1,384

£1,000 in 2015 → 2024

Delta: +£384
Cumulative: 38.4%
Annualised: 3.68%
Direction: forward, 9 years

How this is calculated

We apply the ratio of the ONS Consumer Prices Index (CPI, series D7BT) between the two years — the same method used by the Bank of England's public inflation calculator. For example £100 in 2015 scales by 138.4 / 100.0 = 1.384 to give £138.40 in 2024.

The annualised rate is the compound inflation per year required to turn the start value into the end value over the period. The cumulative figure is the total change over the whole span.

Source: ONS D7BT timeseries. Dataset uses ONS annual averages — for sub-year granularity consult the ONS website directly.

Popular inflation lookups

Common starting points — each a dedicated page with the CPI-adjusted value and context for that year.

This UK inflation calculator uses official ONS Consumer Prices Index data (series D7BT) to adjust any pound amount between two years. The same series HMRC and the Bank of England cite as the headline UK inflation measure.

How to read the result

Adjusted amount is the CPI-equivalent of your input in the target year. If you put in £1,000 in 1990 and look at 2024, the calculator shows what that 1990 pound had the purchasing power of in 2024 money — historically UK inflation has eroded the pound about 2.7× since 1990.

Cumulative change is the total percentage inflation over the whole period. Going from 2015 to 2024 the cumulative CPI rise is 38.4%, meaning goods that cost £100 in 2015 cost £138.40 on average by 2024.

Annualised rate is the compound inflation rate per year you’d need to get from the start value to the end value over that span. The UK long-run average is around 2–3% per year.

Why direction matters

Forward (past → present): you start with an older pound amount and ask “what would that be worth today”. Typical use: translating an older salary, house-price, or gift of money into today’s equivalent.

Backward (present → past): you start with today’s amount and ask “what was this worth back then”. Typical use: historical comparisons, “what did my parents earn relative to me” conversations, or sanity-checking old wage statistics.

Data sources & cadence

CPI index: ONS D7BT — updated monthly by ONS; we store annual averages.
Update frequency: once a year (January) after ONS publishes the previous year’s annual average.
Coverage: 1990 onwards. ONS has further history back to 1988 for the series itself, and to 1914 via linked older series.

Our methodology page lists every data source with retrieval dates and links to the raw ONS timeseries.

Salary vs inflation — see how your salary tracks against UK CPI over the past 15 years.
Salary calculator — translate a gross salary into take-home for 2026/27.
UK cost of living by city — regional variation in rent, council tax and median pay.
UK salary statistics — where common salaries rank against national percentiles.

Frequently asked questions

Where does the CPI data come from?: ONS series D7BT — the official UK Consumer Prices Index (All Items), indexed to 2015 = 100. This is the same series HMRC, the Bank of England and the Treasury cite for inflation measurement. We use annual averages.
What is the difference between CPI and RPI?: CPI (D7BT) is the government's preferred measure since 2010 and is used for most state benefits and the Bank of England's inflation target. RPI (older series) is still used for some legacy indexations (rail fares, some student loans) but the ONS no longer treats it as a "national statistic". We use CPI.
Is this the same as the Bank of England inflation calculator?: Results should match to within rounding. Both use ONS D7BT annual averages. Minor differences can arise from which index point each tool uses (annual average vs a specific month).
Why can I only pick certain years?: Our dataset uses ONS annual averages. Earlier data (pre-2015) is provided at 5-year intervals; from 2015 onwards every year is covered. Sub-year granularity (monthly CPI) is possible via the ONS website directly.
Does this account for regional differences?: No — CPI D7BT is a single UK-wide index. ONS publishes regional price-level comparisons separately (Relative Regional Consumer Price Levels) but not regional inflation time series. London costs are typically 10 to 15 percent higher than the national average, which CPI does not capture directly.