Inflation and Real Returns: What Your Money Can Buy
Separate growth in your balance from changes in what it can buy.
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Same basket; changing purchasing power
Plain English
Money amounts and buying power
A money balance can grow while its ability to buy things grows much less. The nominal return describes the change in the money amount. The real return describes the change after allowing for prices. Neither description replaces the other: they answer different questions about the same period.
Inflation means an increase in a general price level, commonly measured using an index. An index follows a specified basket of goods and services rather than the price of every purchase made by every household. A 3% rise in that index means the measured basket costs 1.03 times its earlier price. It does not mean every individual price rose by 3%.
To compare buying power, put the ending balance into the purchasing units of the starting date. That requires division by the change in the price level. Subtracting inflation from a nominal return is a useful approximation when the rates are small, but division gives the exact relationship for the assumed figures.
Worked Example
The same money, expressed in earlier prices
Suppose £1,000 earns a hypothetical 5% nominal return over one year, with no fees, taxes, deposits or withdrawals. The balance becomes £1,050. Assume a relevant price index rises by 3% over exactly the same year. These are teaching assumptions, not current inflation data or a forecast.
A basket costing £1,000 at the beginning would cost £1,030 at the end if its price followed that index. Divide the £1,050 balance by 1.03 to express it in beginning-of-year purchasing power: £1,019.42, rounded to the nearest penny. Relative to the original £1,000, the exact real increase is approximately 1.94%, rounded to two decimal places.
The calculation uses growth factors: 1.05 describes the money balance and 1.03 describes the price level. Dividing one by the other compares how fast money and prices changed. Subtracting one converts that ratio into a return.
Formula
Real return equals one point zero five divided by one point zero three, minus one
Rates cover the same year; the decimal result is approximately 1.94%.
Starting balance
£1,000.00
Ending nominal balance
£1,050.00
Ending balance in starting purchasing power
£1,019.42
Real return
1.94%
Reading the result
Two valid descriptions of the gain
The £50 nominal gain has not disappeared. Some of it compensates for the higher cost of the assumed basket. The real calculation says that the ending balance buys about 1.0194 times the starting basket, rather than 1.05 times it. This is a comparison of purchasing power, not a separate cash payment.
Simply subtracting 3% from 5% produces 2%, slightly above the exact 1.94%. The ECB explainer uses the subtraction convention to introduce nominal and real rates. Here the division makes the approximation visible. A larger gap between price levels can make the difference more noticeable, especially when comparisons extend across several periods.
Limits and assumptions
Whose basket is being measured?
A household spending heavily on rent, energy or particular services may experience a different change in costs from the published index. That difference does not automatically make the index wrong. It means the index and the household weight purchases differently. The choice of index should match the question being asked as closely as the available information allows.
Actual investment outcomes can also involve fees, taxes and uncertain prices at the point of sale. This example excludes those effects to isolate inflation. A quoted nominal return and a forecast inflation rate do not establish a known future real return. For comparisons over several years, compound the relevant changes over matching dates rather than adding annual percentages together.
A useful comparison also distinguishes information known afterwards from expectations formed beforehand. Once the year has ended, both the nominal outcome and measured inflation can be observed. Before it starts, one or both may be uncertain. The same formula organises those inputs, but it does not turn an expectation into an observed result.
Common Mistake
Treating a bigger balance as an equal improvement
Seeing £1,050 where there used to be £1,000 can encourage a claim that spending capacity improved by 5%. That statement skips the price comparison. Equally, describing inflation as a fee deducted from the account is misleading: inflation changes what money buys, while a fee changes the money remaining. Keeping those mechanisms separate makes both easier to understand.
Self-check
Check your understanding
Why divide £1,050 by 1.03?
The divisor removes the assumed 3% rise in the price level, expressing the ending money in starting-date purchasing power.
Is the exact real return 2%?
No. Subtraction gives an approximation. The exact ratio, 1.05 divided by 1.03 minus one, is about 1.94%.
Must every household experience 3% inflation?
No. A measured basket has specified weights. A household with different purchases can experience a different change in its own costs.
Continue learning
Connect the ideas
Follow the related articles below to explore the assumptions behind this example.
Disclaimer
Educational Use Only
This article is for informational and educational purposes only. It does not provide personalised investment advice.
