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

£1,464

£1,000 in 2015 → 2026

Delta: +£464
Cumulative: 46.4%
Annualised: 3.53%
Direction: forward, 11 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. CPI is the headline UK inflation measure cited by HMRC, the Bank of England, the Office for Budget Responsibility, and the Office for National Statistics.

How to use this calculator

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 family gift into today’s equivalent buying power.

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

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 2026, the calculator shows what that 1990 pound has the purchasing power of in 2026 money - historically UK inflation has eroded the pound about 2.8× since 1990.

Cumulative change is the total percentage inflation over the whole period. Going from 2015 to 2025 the cumulative CPI rise is approximately 38.4%, meaning goods that cost £100 in 2015 cost about £138 by 2025.

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. UK long-run average is around 2-3% per year, with sharp spikes during oil crises (1970s), boom-bust (late 1980s, late 2000s), and the post-COVID 2022-2024 inflation surge that peaked at 11.1% headline CPI in October 2022.

Why CPI matters for UK tax and benefits

UK income tax bands, National Insurance thresholds, and most benefit levels are uprated using CPI (or sometimes the slower CPIH measure):

Income Tax thresholds: frozen 2021-2030 (Personal Allowance, basic rate threshold, higher-rate threshold, additional-rate threshold all unchanged in nominal terms - a deliberate “fiscal drag” policy worth £40bn+ over the freeze period).
State Pension: triple-locked to higher of CPI / earnings / 2.5%.
Universal Credit + most benefits: CPI-indexed annually each April.
National Living Wage: set by Low Pay Commission with reference to CPI + median earnings target (66% of median).
ISA + pension allowances: frozen since 2017/18 (£20k ISA) and 2023/24 (£60k AA) - massive cumulative fiscal drag.

When tax thresholds freeze AND inflation rises, more people are pushed into higher tax bands without earning real income. The £100,000 PA taper threshold has been frozen since 2010 - CPI-adjusted that’s equivalent to ~£175,000 in 2010 money.

CPI vs CPIH vs RPI vs RPIX

UK has several inflation measures with different methodologies:

Measure	What it covers	Typical level	Used by
CPI (D7BT)	Goods + services, excludes housing	Headline	HMRC, BoE, ONS, this calc
CPIH	CPI + owner-occupied housing	Slightly higher than CPI	ONS preferred since 2017
RPI	Older measure, includes mortgages	Higher than CPI	Index-linked gilts, some pensions
RPIX	RPI excluding mortgage payments	Volatile	Legacy use
GDP Deflator	Whole economy	Lower	Government economic modelling

RPI is being phased out from 2030 in favour of CPIH for all official UK statistics. This calculator uses CPI (D7BT) as the universally cited modern measure.

Worked examples

Translating a 1995 salary to 2025 money:

1995 salary: £25,000
CPI 1995: 60.3
CPI 2025: 143.1
2025 equivalent: £25,000 × (143.1 / 60.3) = £59,326

So a £25k salary in 1995 had the purchasing power of about £59k in 2025.

Historical investment growth:

£10,000 invested in 1990
2025 nominal value (assume 5% annual growth): £55,160
2025 real value (CPI-adjusted to 1990 pounds): £55,160 ÷ 2.82 = £19,560
Real return: 96% over 35 years = ~2% real annual return

This is why financial planning needs to distinguish nominal returns from real returns. A 5% nominal return in a 3% inflation environment is only ~2% real growth.

House price inflation comparison:

1995 average UK house price: £55,000
2025 average UK house price: £281,000 (HM Land Registry March 2025)
Nominal increase: 411%
CPI-adjusted 1995 price in 2025 money: £130,500
House prices have outpaced CPI by ~2.15× since 1995

Real estate has been a clear winner against CPI but the gap reflects supply-constrained housing market dynamics more than monetary inflation.

Data sources and 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 back to 1914 via linked older series (we may add these later).
Annual average vs December value: we use the annual average for comparability. The December value can differ - the headline “inflation rate” you see in the news is December-on-December change for CPI.

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

Limitations

Average not personal: CPI is calculated from a basket of goods representing typical household spending. Your personal inflation experience may be higher or lower depending on what you spend on. Higher-housing-cost households experienced higher real inflation 2022-2024 than average CPI suggested.
Quality adjustments: ONS adjusts for quality improvements (e.g., computers are faster than 10 years ago for same price). Some argue this understates “real” inflation for consumers.
Owner-occupied housing: CPI excludes mortgage interest + imputed rent. If housing is a large part of your costs, CPIH is more representative.
Investment + savings: this calculator translates PURCHASING POWER not investment returns. To compare investment returns, use real-rate formulas.

Salary vs inflation - see how your salary tracks against UK CPI over the past 15 years
Cost of living by city - regional variation in rent, council tax and median pay
Salary calculator - translate gross salary into take-home for 2026/27
UK salary statistics - where common salaries rank against national percentiles
UK pounds inflation calculator guide - detailed explainer including fiscal drag mechanics
State Pension guide - triple-lock CPI uprating
How tax works - thresholds frozen vs CPI uprating
Tax deadlines 2026/27 - all annual UK tax dates

Sources

CPI series D7BT from Office for National Statistics, monthly updates. Statutory basis for CPI use: Bank of England Act 1998 (BoE inflation target framework), Welfare Reform Act 2012 (benefit uprating), Pensions Act 2014 (triple-lock).

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.

Browse UK inflation by amount

Pre-calculated UK CPI inflation adjustments for 7 popular pound amounts. Forward + backward inflation conversion 1990 to 2026, ONS D7BT series throughout.

Other UK tax calculators that pair with the Inflation.