Real return on UK savings: how inflation turns a 4.5% nominal rate into ~1.1% in your pocket

What "real return" actually means

A savings account's nominal interest rate is the headline figure: a 4.5% account pays £45 a year on £1,000. The number is mathematically accurate. It is not, however, what the saver actually gains in spending power, because prices typically rise over the same year. Real return is the nominal rate adjusted for inflation, and it is the number that tells the saver whether their money is growing or shrinking against the cost of living.

The relationship is captured in the Fisher equation: real return ≈ nominal rate − inflation rate. A 4.5% nominal rate with 3.4% inflation gives a real return of approximately 1.1%. The £45 of interest is real money, but the £1,000 principal can buy 3.4% less than it could a year earlier, so the net gain in purchasing power is just £11 on the £1,000.

UK CPI inflation sat at around 2.8% in the year to May 2026 per the ONS consumer price inflation release, with the Bank of England's June 2026 MPC projecting it to reach 3.25% in the final quarter of the year. The 3.4% figure used above is a reasonable working estimate for late-2026 conditions; the actual figure to apply is the latest ONS CPI rate at the time of the calculation.

The precise Fisher equation

The approximate formula (real ≈ nominal − inflation) is accurate enough for most consumer applications, but the precise calculation is:

(1 + real rate) = (1 + nominal rate) / (1 + inflation rate)

Rearranged: real rate = (1 + nominal rate) / (1 + inflation rate) − 1

Applied to 4.5% nominal and 3.4% inflation:

• 1 + nominal = 1.045
• 1 + inflation = 1.034
• 1.045 / 1.034 = 1.01064
• Real rate = 1.064%, or rounded to 1.1%

The approximation (4.5% − 3.4% = 1.1%) lands within 0.04 percentage points of the precise answer at these rate levels. For inflation above 5% or savings rates above 6%, the approximation drifts further and the precise calculation matters more.

Real return across different rate environments

The same nominal rate produces different real returns depending on the inflation environment. The table below uses the precise Fisher calculation; figures are rounded to one decimal place.

Nominal rate	At 2.0% inflation	At 3.4% inflation	At 5.0% inflation
3.0%	+1.0% real	−0.4% real (loss)	−1.9% real (loss)
4.5%	+2.5% real	+1.1% real	−0.5% real (loss)
5.5%	+3.4% real	+2.0% real	+0.5% real
7.0%	+4.9% real	+3.5% real	+1.9% real

The 2022/23 UK environment had peak inflation above 10% with savings rates climbing to roughly 6%. The real return on a 6% account during 11% inflation was about −4.5%: savers were losing roughly 4.5% of purchasing power per year despite nominal interest income. The 2026 environment with savings rates around 4.5% and inflation around 3.4% delivers a positive real return of around 1%, the first sustained positive territory since 2021.

Worked example: £50,000 over 5 years

A saver holds £50,000 in an easy-access savings account at 4.5% nominal, with inflation averaging 3.4% per year for 5 years.

Nominal calculation (compound):

• Year 0: £50,000
• Year 5: £50,000 × (1.045)⁵ = £62,310
• Nominal gain: £12,310

Real calculation (purchasing power):

• Year 5 nominal balance: £62,310
• Inflation factor over 5 years: (1.034)⁵ = 1.182
• Year 5 balance in Year-0 purchasing power: £62,310 / 1.182 = £52,720
• Real gain in Year-0 spending power: £2,720
• Real return rate (annualised): approximately 1.064% per year

The saver's nominal balance grew by £12,310, but their actual spending power grew by only £2,720 over the 5-year period. The remaining £9,590 of nominal gain was absorbed by the loss of purchasing power on the original £50,000 plus the accumulated interest.

Calculate Your Savings Growth → (use to model the nominal compound interest at different rates; subtract the inflation-adjusted purchasing-power loss separately to get the real return figure.)

Why real return matters more than nominal

Three practical consequences follow from focusing on real rather than nominal returns:

Account comparison gets sharper. Two savings accounts at 4.5% and 4.7% nominal differ by 0.2 percentage points in headline terms. At 3.4% inflation, their real returns are 1.06% and 1.26% respectively. The 0.2pp nominal gap translates to roughly a 19% relative difference in real return (£11 vs £13 of purchasing-power gain per £1,000 per year). Small nominal differences are larger in real terms than they appear.

Cash vs equities looks different in real terms. Long-run UK equity real returns have historically averaged 5% to 7% per year (CPI-adjusted). At 1% real return on cash and 5% real return on equities, the gap is 4 percentage points per year of real wealth accumulation, compounded over the holding period. This is the foundation of the policy intent behind the April 2027 Cash ISA cap (£20,000 to £12,000 for under-65s): to nudge savers toward higher-real-return investment products.

Fixed-rate decisions sharpen. Locking in a 5-year fixed-rate savings bond at 4.5% is a bet that average inflation over the 5 years will be below 4.5%. If inflation averages 3%, the real return is 1.5%. If inflation averages 5%, the real return is −0.5%. The decision is implicitly a forecast about the inflation path.

Where to find current UK inflation data

The Office for National Statistics publishes the official UK inflation rate each month, typically on the third Wednesday. The ONS Inflation and price indices hub carries the latest CPI, CPIH, and RPI figures with downloadable time-series data. The Bank of England inflation calculator lets a saver test what £X was worth in a given year vs today using the historical CPI series.

For UK personal-finance decisions, CPI is the most commonly used inflation measure (it is the Bank of England's 2% target metric and the basis for most rate-decision context). CPIH (which includes owner-occupier housing costs) is the ONS's preferred headline measure but is less widely cited in financial commentary. RPI is still used to uprate some legacy products (rail fares, student loans on certain plans, index-linked gilts) but the ONS removed its National Statistic status because of known technical issues; do not use RPI for real-return calculations on savings accounts.

Frequently asked questions

Is the Fisher equation always accurate?

The approximation (real ≈ nominal − inflation) is accurate within 0.05 percentage points at consumer-rate levels (savings rates below 6%, inflation below 5%). At higher rates and inflation levels, the precise formula (1+nominal)/(1+inflation) − 1 differs more meaningfully and should be used.

What inflation rate should I use for my own calculation?

The latest CPI figure from the ONS Inflation and price indices hub, unless the calculation specifically calls for a different measure. For long-term planning, the Bank of England's 2% CPI target is sometimes used as a forward assumption, but actual inflation has averaged closer to 2.5% to 3% over the last 25 years and was notably higher in 2022/23.

How does real return interact with the Personal Savings Allowance?

The PSA is the threshold above which savings interest becomes taxable: £1,000 for basic-rate taxpayers, £500 for higher-rate, £0 for additional-rate (HMRC, Apply for tax-free interest on savings). For interest beyond the PSA, the tax bill reduces nominal interest income, which in turn reduces real return. A higher-rate taxpayer with PSA exhausted earning 4.5% nominal has a post-tax nominal rate of 2.7%; at 3.4% inflation, that is a real return of approximately −0.7%.

Does the same calculation apply to investment returns?

Yes. Real return is calculated the same way for equity returns, bond returns, and savings interest: nominal return minus inflation. The interpretation differs because equity returns are far more volatile, so the real return varies dramatically year to year even at stable inflation levels.

Where is the live UK inflation figure?

The ONS Inflation and price indices hub publishes the monthly CPI release. The GOV.UK Consumer price inflation statistics summary provides the official commentary alongside the data.

Further reading

• ONS Inflation and price indices: monthly CPI, CPIH, RPI data with downloadable time series
• Bank of England inflation calculator: historical purchasing-power calculator using CPI
• GOV.UK Consumer price inflation statistics summary: official monthly inflation commentary
• MoneyHelper Savings hub: MaPS consumer guidance on savings choices and inflation context