Compound interest calculator
See how a starting amount and regular monthly payments could grow over time when the returns are reinvested.
Your projected growth
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How compound interest works
Interest on interest
Compound interest means you earn returns on your original money and also on the returns already added. Over short periods the effect is small. Over many years it grows quickly, which is why starting early matters more than most people expect.
The effect of regular payments
Adding a regular amount each month does most of the work in the early years. In later years the growth on the pot itself becomes larger than what you pay in. Try changing the number of years to see where the lines cross.
Tax and charges
This calculator shows growth before tax and fees. Savings interest, dividends and gains may be taxable outside an ISA or pension, see how is savings interest taxed. Fund charges reduce the return, so a yearly return of 5% before fees is closer to 4% after a 1% charge.
What this calculator assumes
- The return is a steady yearly rate, compounded monthly.
- Payments are made at the end of each month.
- There is no tax, inflation or charges. Prices usually rise over time, so the real buying power of the final figure is lower.
- Past returns do not guarantee future returns, and investments can fall as well as rise.
Questions people ask
How much is my money worth after 10 years at 5%?
If you pay in £200 a month with £1,000 to start, the pot grows to about £32,700, of which £25,000 is what you paid in. The rest, about £7,700, is growth.
What is a realistic yearly return?
It depends on where the money is held. Cash savings pay interest rates that follow the Bank of England rate. Investments such as shares have historically returned more over the long run but with more ups and downs. Treat any figure as an assumption, not a promise.
Is it better to pay in a lump sum or monthly?
A lump sum has longer to grow, but monthly payments are easier for most people to keep up. Using your ISA allowance each year is a sensible habit, see the savings calculator.
Is what I type stored or shared?
No. The calculation runs in your browser and nothing you enter is sent to us. Our privacy page has the details.
Is this financial advice?
No. It gives an estimate for information only. For advice about your own situation, speak to a regulated adviser.