Compound Interest Calculator
Estimate future value with compound interest and contributions.
Estimate
How compound interest works
Compound interest means earning interest on your original balance and on interest already added. Over longer periods, that compounding can make a substantial difference to growth.
Example: £1,000 growing at 5% a year would become £1,050 after one year. If the interest is compounded annually, the next year's 5% is calculated on £1,050 rather than the original £1,000.
Regular contributions can increase the final balance further because each contribution can also begin earning interest. Actual returns can differ from an estimate, so calculator results are illustrative rather than a guarantee of future performance.
How to use the Compound Interest Calculator
Enter a starting balance, annual contribution, estimated annual rate and number of years. UsefulFox compounds the balance annually and shows an illustrative future value.
Compound interest example
Starting with £5,000, adding £1,200 each year and earning an illustrative 5% annually for 10 years produces a future value above the amount contributed because earlier interest can itself earn interest.
Why does compounding matter?
Compounding means returns are applied to the existing balance, including earlier growth. Time, contributions and the assumed rate can therefore have a large effect on the estimate.
Frequently asked questions
1Is the interest rate guaranteed?
No. The rate is an assumption for illustration; actual savings or investment returns can be higher or lower.
2When are contributions added?
This calculator models the annual contribution before that year's interest is applied.
3Does it include tax or fees?
No. Taxes, charges and product fees are not included and can reduce real-world returns.
4What is compound interest?
It is interest calculated on a balance that includes earlier interest, allowing growth to build on previous growth.