The formula
For a single amount:
Future value = P × (1 + r ÷ n)^(n × t) P = starting amount, r = annual rate, n = compounding periods per year, t = years
The calculator simulates growth month by month so it can combine any contribution frequency with any compounding frequency. Contributions are added at the end of each period.
Make your money work harder
- Start early: time in the market matters more than the amount.
- Increase contributions when your salary increases.
- Keep fees low — a 1% annual fee can cost a large share of your final value over decades.
Worked examples
R1 000 a month for 20 years at 9%
You contribute R240 000 and compounding grows it to about R668 000 — most of the final value comes from growth in the later years.
Increasing your contribution with your salary
Raising the monthly amount by 6% a year has a dramatic effect on the final balance.
Frequently asked questions
What is compound interest?
Interest earned on both your original money and the interest it has already earned. Over long periods, growth on growth becomes the biggest part of your balance.
What return should I use?
For a bank savings or fixed deposit account, use the rate the bank quotes. For investments such as unit trusts or ETFs, use a realistic long-term return after fees, and remember returns vary from year to year.
Is interest on savings taxed?
Interest from South African sources is exempt up to R23 800 a year if you are under 65 (R34 500 if 65 or older). Above that it is taxable. A tax-free savings account (up to R46 000 a year) is not taxed at all.