How the saving is calculated
The calculator runs your bond month by month twice — once with your normal repayment and once with your extra payments (and any lump sum applied today). Each month, interest is charged on the outstanding balance at your rate ÷ 12, and the rest of the payment reduces capital.
Interest saved = interest without extra payments − interest with extra payments Time saved = months to settle without − months to settle with
If you leave the current repayment empty, it is calculated as the instalment needed to repay the balance over the remaining term.
Worked examples
R1 000 extra a month on a R1.1 million balance
Adding R1 000 a month to the repayment goes straight to capital, shortening the bond by years and saving a large amount of interest.
Without extra payments
- Remaining balance
- R1 100 000.00
- Monthly repayment
- R11 760.96
- Paid off in
- 17 years
- Interest still to pay
- R1 299 235.72
Paying a R50 000 bonus into the bond
A lump sum early in the loan saves far more interest than the same amount paid near the end.
Without extra payments
- Remaining balance
- R1 100 000.00
- Monthly repayment
- R11 760.96
- Paid off in
- 17 years
- Interest still to pay
- R1 299 235.72
Frequently asked questions
Is it better to pay extra into my bond or invest?
Paying extra saves interest at your bond rate, tax-free and risk-free. If your bond rate is higher than the after-tax return you can expect from investing, extra bond payments usually win.
Can I get the extra money back?
On most access bonds you can withdraw amounts paid in advance, but some banks charge a fee or limit withdrawals. Check your bond agreement.
Does the bank automatically reduce my term?
Usually extra payments reduce the balance and therefore the term if you keep paying the same instalment. Some banks recalculate the instalment instead — ask your bank how it treats them.