Compound interest can grow your money dramatically over time. Inflation is compound interest working against you — steadily eroding the purchasing power of your savings. Understanding how these two forces interact is essential for building real, rather than just nominal, wealth.
At 2% annual inflation (the Bank of England's target), prices double roughly every 36 years (the Rule of 72 applied to inflation: 72 ÷ 2 = 36). What costs £1 today will cost £2 in 36 years. Your savings need to at least match inflation to preserve their purchasing power.
This is why leaving money in a low-interest current account destroys real wealth. If your savings earn 1% but inflation runs at 3%, your real return is -2% per year. On £10,000, that is £200 of real wealth lost annually — silently, without any explicit charge.
The concept here is the real interest rate: the nominal rate minus inflation. If your savings account pays 4% and inflation is 3%, your real return is 1%. This is what your money is actually growing by in terms of purchasing power.
For investments, the same distinction applies. If your portfolio returns 7% per year but inflation averages 3%, your real return is approximately 4%. This 4% is what represents genuine growth in your wealth. The 3% nominal gain that matches inflation is just keeping up — not getting ahead.
Over a 40-year investment horizon, these differences compound into enormous absolute amounts. A 7% nominal return with 2% inflation gives a 5% real return. At 5% real, £10,000 grows to approximately £70,400 in real terms after 40 years. If inflation were 4% (real return 3%), it grows to only £32,600. The difference in real wealth from seemingly small inflation differences is substantial.
Inflation-eroding real returns is one of the most compelling arguments for investing in assets that historically outpace inflation — equities, property, and inflation-linked bonds — rather than holding cash.