Compound Interest Calculator — United Kingdom
See what regular saving grows to over time, and how much of the result is growth rather than your own contributions. Figures below assume a 7% annual return over 20 years. Free, and no sign-up.
What regular saving grows to
| You save | Total contributed | Worth after 20 years |
|---|---|---|
| £100 / month | £24,000 | £52,093 |
| £250 / month | £60,000 | £130,232 |
| £500 / month | £120,000 | £260,463 |
| £1,000 / month | £240,000 | £520,927 |
Frequently asked questions
How does compound interest work?
Each period your balance earns a return, and that return then earns a return of its own. Over long horizons the growth on past growth comes to outweigh what you contributed.
What return should I assume?
Long-run share market averages have sat around 7–10% a year before inflation, but real returns vary a lot year to year. Treat any single figure as a shape, not a promise.
Is this calculator free?
Yes. No account, no sign-up, and nothing you enter leaves your browser.
Work out your own numbers
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Estimate only. Assumes a constant return and ignores tax, fees and inflation. Not financial advice.