RandRoute · South African money tools
Compound interest explained with a South African example
Last reviewed: 6 October 2026 · South Africa-focused
Short answer
A projection should show what you deposited and what the assumed return could add. This makes the result easier to question and adjust.
Separate contributions from growth
A projection should show what you deposited and what the assumed return could add. This makes the result easier to question and adjust.
Time changes the result
A longer horizon gives growth more time to build on previous growth. Regular contributions can matter as much as the starting balance.
Treat returns as assumptions
Investment returns are not guaranteed. Test a lower rate, account for fees and tax where relevant, and avoid using a projection as a promise.
Worked South African example
For example, set a R100,000 goal, start with R10,000, and choose a 24-month timeframe. Use the monthly contribution as the number to test against your budget.
Put the idea into a number
- Compound Interest Calculator — Project how a starting amount and regular monthly contributions could grow over time.
- Savings Goal Calculator — Work out how much to save each month to reach a target amount by a chosen date.
- Monthly Savings Calculator — Calculate the monthly saving needed to reach a target without assuming investment growth.
- Emergency Fund Calculator — Estimate an emergency fund target from essential monthly expenses and the gap you still need to cover.
Next step: Start with the primary calculator above, then compare the next two tools to turn the guide into a plan.