Calculators

Compound interest calculator

See how a lump sum and regular monthly amounts could grow over time, and how much fees could cost you.

£
£
%
%
£75,939Could grow to
£36,000You'd pay in
£39,939Growth
Total value Amount paid in

How this calculator works

It adds your monthly amount at the end of each month and grows the total by your yearly growth rate, minus your yearly fees, compounded monthly. It's an illustration, not a prediction.

  • Real returns go up and down. Investments don't grow at a steady rate, and you could get back less than you put in.
  • It ignores inflation. Rising prices mean money in the future buys less than it does today.
  • It ignores tax. That's broadly how ISAs and pensions work, but other accounts may be taxed.

Nothing you enter is stored or sent anywhere. Everything is worked out in your browser.

What is compound interest?

Compound interest means earning growth on your past growth, not just on the money you put in. Over time, that growth can end up larger than everything you paid in. That's why starting early, and keeping fees low, can make such a big difference.

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