Comparing returns fairly

Two investments sit in front of you. One shows an average investment return of 10%. The other shows 7%. In this example, the instinct is to reach for the bigger number. That instinct can mislead you if you do not ask what earned it.

A return figure without context can be misleading. The same headline number can come from a steady climb or from a much more volatile path with large drawdowns. Comparing returns fairly is not about finding the highest figure. It is about knowing what the figure actually represents.

Why this matters

Return figures show up everywhere, and they invite quick comparisons. But a return without its context is a verdict without a trial.

If you ignore context, you can end up choosing an investment that looks best on paper but feels unworkable in practice. Big swings can make it harder to stay invested or can lead some people to sell during downturns.

A fair comparison protects the decision. It forces you to ask what risk produced the return, what period it covers and whether inflation has already taken a bite. Without those answers, you are not comparing like with like.

The idea in plain English

A return is simply growth or loss over a period of time. If you put in £1,000 and end with £1,070 a year later, your return is 7% for that year. An average investment return stretches the same idea across multiple years, summarising the highs and lows into a single figure. Average can mean an annualised (geometric) return over the period or an arithmetic average of yearly returns; these can differ. Check which measure is being used.

Headlines often show nominal returns (before inflation), but presentation varies. Check the source to see whether returns are nominal/real and whether they’re annualised. If prices rose 3% over the same period, your real return (the gain in actual buying power) is closer to 4%. Real return vs nominal return is not a technicality. It changes what the number means in day-to-day terms.

A headline return also hides the path. Two investments can land on the same average while taking very different routes. One may have moved in a narrow band. The other may have swung from sharp gains to sharp losses. The average looks identical, but the risk taken to earn it may be very different.

The key points to understand

Higher returns usually come with higher risk. A large figure often signals larger swings and a wider range of possible outcomes. Volatility is one way of describing how bumpy those swings can be.

Time period changes everything. A one-year figure and a five-year average cannot sit next to each other and mean the same thing. Match the period and match the type of return before you compare.

Nominal return is the headline. Real return is what remains after inflation. An inflation-adjusted return is another way of describing a real return, because it aims to show changes in buying power, not just the number on the screen.

The average hides the path. A fund that earned 7% per year on average may still have had deep drawdowns along the way. If you might need access to your money during a downturn, that path matters.

Past performance is not a reliable indicator of future results. The value of investments can fall as well as rise, and you may get back less than you invest.

A simple example

Two funds both show an average return of 7% a year over five years. On paper, they look equal.

Fund A moved in a narrow band. Each year its return stayed between 5% and 9%. The ride was relatively steady and the experience broadly matched what the average suggested.

Fund B swung from plus 25% one year to minus 18% the next. It recovered, dipped again, then climbed. Over five years the maths lands on the same 7% average. But the experience was not alike. If you needed to withdraw during a down year, you could have locked in a loss that the average did not warn you about.

Now add inflation. Suppose prices rose by an average of 3% per year over the same period. The nominal return for both funds is 7%. The real return, the inflation-adjusted return, is closer to 4%. That is the gain in buying power.

These figures are illustrative. They are not forecasts or guarantees. The point is the method, not the numbers.

How to use this in your next decision

When you want to work out how to compare investment returns, use a repeatable checklist.

First, match the period. Compare one year to one year, five years to five years. If the time frames differ, the comparison is not meaningful.

Second, check the definition of return. Confirm whether each figure is nominal or real. If one figure has stripped out inflation and the other has not, you are comparing different measures.

Third, look at the range of outcomes, not just the average. What were the best and worst years? How often did the return fall sharply? A fund performance comparison that ignores volatility ignores a key part of risk.

Fourth, ask what risk earned the return. If one option achieved its results with much larger swings, that higher headline figure may come with a wider range of possible outcomes.

Fifth, keep the limits of the data in mind. Past performance is not a guide to future results. Use the history to understand behaviour and risk, not as a promise.

This is a framework for judgement. It is not personal advice. Your own circumstances, goals and tolerance for risk will shape how you use it. This information is for education only and does not consider your personal circumstances.

Common mistakes

Chasing the highest headline figure without checking the risk or period behind it: The biggest number often comes with the biggest swings.

Comparing a nominal return in one place against a real return in another: The comparison can look decisive but mean very little.

Treating a single strong year as a reliable guide to what comes next: One exceptional year can distort an average and create unrealistic expectations.

Ignoring the time period behind the number: A fund that returned 15% over three years is not directly comparable to one that returned 10% over one year. Match the periods before you draw conclusions.

Key takeaways

• A return means little until you know the risk, the period and whether inflation has been stripped out.

• Higher returns tend to carry higher risk and wider swings.

• Real return, after inflation, is the figure that reflects buying power.

• Only compare returns over matched periods and matched definitions.

• The average hides the path. Look at the range of outcomes as well.