Bond Repayment
Know what your bond actually costs. Before you sign.
Punch in your numbers and see what the bank is actually charging you.
- Purchase Price
- R 2 000 000
- Deposit
- R 200 000
- Loan Amount
- R 1 800 000
- Interest Rate
- 11.25% per year
- Term
- 20 years
- Monthly Repayment
- R 18 887
- Total Repaid
- R 4 532 786
- Total Interest
- R 2 732 786
That's a lot of interest. The bank thanks you for your service.
Outstanding balance over time
How bond repayments are calculated
Your monthly bond repayment is calculated from three numbers: the loan amount (purchase price minus deposit), the interest rate, and the term in years. The bank spreads the loan and all the interest it will charge over equal monthly instalments, so the repayment stays the same each month even though the split between interest and capital shifts over time: early payments are mostly interest, later ones are mostly capital.
That's why the total interest paid over a 20-year bond is often close to, or more than, the amount you borrowed. A higher deposit reduces the loan amount directly; a shorter term, extra monthly payments, or a once-off lump sum reduce how long interest has to accumulate.
Add an extra monthly payment or a once-off lump sum above and this calculator shows you the second effect directly: how many years and how much interest you'd cut by paying more than the minimum.
Results are for illustration only and do not constitute financial advice. Consult a qualified financial adviser before making decisions based on these figures.
A worked example
Say you buy a R1,500,000 property with a R150,000 deposit, at a prime-linked rate of 11.25% over 20 years. The loan amount is R1,350,000, and the monthly repayment comes out to roughly R14,200. Over the full 20-year term, you'd pay close to R2,058,000 in total, meaning total interest of around R708,000, more than half of what you borrowed.
Now add an extra R1,000 a month on top of that repayment from month one. The bond gets paid off just under 4 years early, and total interest drops by roughly R160,000. A small monthly change compounding into a large saving, because it shrinks the balance interest is charged on for the rest of the term.
Run your own purchase price, deposit, rate, and term through the calculator above, then try adding an extra payment or lump sum to see your specific numbers.
This doesn't include bond registration, transfer duty, or initiation costs, only the repayment itself. It also assumes your interest rate stays fixed for the whole term, which isn't true for a prime-linked bond if the repo rate moves.
Results are for illustrative purposes only and do not constitute financial advice.
Frequently asked questions
How is a bond repayment calculated?
Your monthly repayment comes from the loan amount (purchase price minus deposit), the interest rate, and the term in years, spread into equal monthly instalments using the standard amortization formula. The split between interest and capital inside each instalment shifts over time: mostly interest early on, mostly capital later.
How much interest will I pay over the life of my bond?
On a typical 20-year bond at a prime-linked rate, total interest paid often lands close to, or above, the amount you originally borrowed. The exact figure depends on your rate, deposit, and term, so enter your numbers above to see your specific total interest and total repayment.
Does a bigger deposit really make a big difference?
Yes. A deposit reduces the loan amount directly, which lowers both your monthly repayment and the total interest charged over the full term, since interest is calculated on a smaller balance every month for the life of the bond.
What's the difference between extra monthly payments and a lump sum?
An extra monthly payment reduces the balance a little every month for the rest of the term, while a lump sum reduces it all at once. Both shrink the balance interest is charged on; a lump sum applied early in the bond tends to save slightly more per rand because the reduction happens immediately rather than gradually.
Is this bond calculator accurate for South African home loans?
It uses the standard amortization formula that South African banks use for prime-linked and fixed-rate bonds, so the monthly repayment and total interest figures should closely match what a bank quote shows for the same purchase price, deposit, rate, and term. Your actual bank quote may include additional fees (like bond registration or initiation costs) not modelled here.
These results are for illustration only and are not financial advice — always consult a qualified financial professional before making financial decisions.