📊 Inflation Impact Calculator (UK)
See how inflation erodes the value of money over time — and what it means for your savings.
UK inflation impact on real returns is calculated as real return = (1 + nominal) ÷ (1 + inflation) − 1. The Bank of England targets 2% CPI inflation; 2022-23 peaked at 11.1% before falling back to 3.3% by March 2026. The ONS publishes CPI monthly; CPIH (CPI including owner-occupier housing costs) is the ONS's preferred measure.
UK inflation between 2022 and 2024 was the most severe real-purchasing-power shock in 40 years. CPI has since cooled to 3.3% (March 2026 release) — still above the BoE's 2% target but no longer the live emergency it was 30 months ago. The worked examples below reference the 2022-23 peak as historical context; the calculator itself uses whatever inflation rate you input. CPI peaked at 11.1% in October 2022, and even savers locked into 5%+ best-buy fixed-rate bonds lost 5-6% of purchasing power in a single year. This calculator models the inflation impact on cash, equity returns, and real-life cost-of-living items so you can see what your money is actually doing in real terms.
How UK inflation is measured:
- CPI (Consumer Prices Index): the headline rate, published monthly by the ONS. Used for the BoE's 2% target, state pension triple lock, and most benefits uprating. Tracks ~720 representative items.
- CPIH: CPI plus owner-occupier housing costs. The ONS's preferred headline measure, generally less volatile than CPI.
- RPI (Retail Prices Index): legacy measure, used for index-linked gilts, rail fares, and some commercial contracts. Now considered statistically flawed by the UK Statistics Authority but persistent in legal contracts — our UK RPI inflation calculator handles the 1947-to-today conversion specifically.
- Personal inflation rate: ONS publishes a personal inflation calculator weighting basket items to your actual spending pattern — useful because if you own your home outright and don't drive, your personal rate may have been 3-4 percentage points below the 11% peak.
The real-return formula:
Real return = (1 + nominal return) ÷ (1 + inflation rate) − 1
For small percentages this approximates to (nominal − inflation), but at high inflation rates the compounded formula matters meaningfully.
Worked example (2022-23): - Best-buy 1-year fixed-rate bond: 5.5% - CPI inflation: 11.1% - Real return: (1.055 ÷ 1.111) − 1 = −5.0%
A saver in 5.5% nominal bonds lost 5% of real purchasing power in twelve months. Over a 30-year horizon, that single year reduces terminal real wealth materially.
Inflation-hedging assets: - UK equities (FTSE All-Share): typically positive real return over 10-year windows, vulnerable in single-year shocks - Index-linked gilts: contractually linked to RPI/CPI, with a real-yield component - Property: historically inflation-correlated, but real return depends heavily on entry yield - Cash: nearly always negative real return when inflation exceeds 3%. For the tax-free variant of the cash-return arithmetic — best-buy 4-5% Cash ISA rates against current CPI — see the dedicated UK Cash ISA growth calculator.
The calculator outputs cumulative real and nominal returns over 1-40 years, stress-tests against alternative CPI paths, and runs a basic Monte Carlo on inflation-and-return outcomes. For underlying data, the ONS Consumer Price Inflation release and the Bank of England's Monetary Policy Report are the authoritative references.
See how inflation erodes the value of money over time — and what it means for your savings.
How does inflation affect savings?
Inflation erodes the real (purchasing) value of money over time. At 3% annual inflation, $100 today has the same buying power as about $74 in 10 years and $55 in 20 years. To preserve real wealth, your investments must return at least the inflation rate; to grow real wealth they must exceed it.
| Year | Future Price | Purchasing Power | Value Lost |
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How to use this calculator
Takes about 1 minute.
- Enter the current amount of money you want to project
- Set an annual inflation rate (USA ~3%, UK ~2.5%, South Africa ~5% long-run averages)
- Pick the number of years over which to apply the inflation effect
- Click Calculate to see the future cost of the same goods and the lost purchasing power
- Review the year-by-year breakdown to see how the erosion compounds
Try these scenarios
Tap a scenario to load it into the calculator above.
Key concepts
What inflation does. Inflation is the steady erosion of money's purchasing power. At 3% annual inflation, $100 today buys what $74 buys in 10 years and $55 in 20 years. The calculator runs this in reverse: it shows what your future amount is worth in today's dollars.
How it's measured. Headline inflation is the Consumer Price Index (CPI) — a basket of typical household spending. The U.S. BLS, UK ONS, and Stats SA all publish monthly CPI figures. 'Core' inflation strips out volatile food and energy.
Personal inflation differs. Your actual inflation depends on what you buy. Healthcare and college tuition have outpaced headline CPI in the US for decades. Tech goods often fall in price.
Inflation hedges. Historically, stocks, Treasury Inflation-Protected Securities (TIPS), and inflation-linked gilts have kept pace with inflation over long horizons. Cash and nominal bonds lose purchasing power when inflation exceeds their yield.
Long-term averages. The US has averaged about 3% CPI inflation since 1913. The UK averaged 2-3% post-1992 (since inflation targeting). South Africa has run 5-6% over the past two decades. Use a regional average, not the headline of any single year.
Frequently Asked Questions
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