Compound interest calculator

Starting with R10,000 and adding R1,000 a month at 8% for 20 years gives about R638,288. You put in R250,000, and R388,288 of it is interest.

Compound interest is interest earned on your original money and on the interest it has already earned. The longer money stays invested, the larger the share of the balance that comes from interest.

For a lump sum, A = P(1 + r/n)^(nt). A is the final amount, P the starting amount, r the yearly rate as a decimal, n how many times a year interest is added, and t the number of years. The calculator also adds your monthly deposits.

Yes, a little. At the same rate, interest added monthly earns slightly more than interest added yearly, because each month of interest starts earning sooner.

Use the rate on your account for a savings account or fixed deposit. The calculator starts at 8% a year as an illustration of a long-term investment return. Returns on investments go up and down and are not guaranteed.