UK Inflation Calculator

What a past sum of money is worth today, or what today's money will be worth in the future — using real sourced UK inflation rates, not a guess.

✓ Free to use ✓ Sourced rate presets ✓ Forward or backward ✓ Shareable results

Direction

Amount (£)

Number of Years

Inflation Rate

Average Annual Rate (%)

Equivalent Value

Cumulative Inflation

Change

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How this calculator works

Inflation compounds year over year, the same way interest does. This calculator applies Value = Amount × (1 + rate)^years for a forward projection (what a past sum is worth today), or the inverse for a backward comparison (what today's money was worth in the past).

Rather than claiming a precise year-by-year CPI index lookup — which varies by exact month and dataset revision — this uses a sourced average annual rate you can adjust, with presets grounded in real published figures.

Rate presets, sourced

Preset	Rate	Source
Recent UK average (2015-2026)	3.36%/yr	ONS CPI-based, ≈43.9% cumulative over 11 years
Bank of England target	2.0%/yr	Official BoE inflation target
2022 peak inflation period	9.0%/yr	Illustrative — CPI peaked at 11.1% in Oct 2022

Worked example

£100 from 2015, adjusted forward at the recent UK average rate (3.36%/year) over 11 years, is worth roughly £143.84 today — meaning what cost £100 in 2015 costs about £143.84 now, a 43.8% cumulative increase.

Average-rate compounding is a reasonable approximation but won't exactly match official ONS CPI index lookups, which reflect real month-by-month variation rather than a smooth average. For an exact historical figure, use the Bank of England's own inflation calculator.

Frequently Asked Questions

Why isn't this exactly what the ONS calculator says?+

This uses a smoothed average annual rate rather than the actual month-by-month CPI index used by ONS, so results are a close approximation, not an exact match — the underlying real inflation path had years both above and below the average.

Should I use CPI or RPI?+

CPI (Consumer Prices Index) is the UK's official inflation measure and what the Bank of England targets. RPI (Retail Prices Index) is an older measure, generally runs higher, and is being phased out of official use — CPI is the more standard and defensible choice for most purposes. See the real 20-year gap between the BoE target and actual inflation →

Can I use this for salary negotiation?+

Yes — it's a common and reasonable way to argue that a salary should rise at least in line with inflation to maintain the same real purchasing power, though employers may reasonably also weigh company performance and market rates.