Extra bond payment calculator
See what paying more into your bond could save you. Enter your outstanding balance, add an extra monthly amount or a once-off lump sum, and get an instant estimate of the term you could shave off and the interest you could save.
How much could paying extra save you?
These numbers are illustrative estimates, not an offer and not guaranteed savings. Your actual rate, recalculation and prepayment terms depend on your bank's assessment and its fee schedule.
Last updated: 2026-09-12. Prime is shown as 10.5%. Your actual rate depends on your credit profile, deposit and the bank’s assessment. Figures are illustrative estimates, not a quote or a guarantee of savings.
Get your personalised extra-payment payoff report
Your new term and interest saved, for your actual bond — computed from the numbers you entered above, assumptions stated — emailed instantly.
What each extra amount saves you
At your current balance, rate and remaining term, this is what each standard extra-per-month amount would do — estimates with the same assumptions as the calculator above.
| Extra per month | Term shortened by | Interest saved |
|---|---|---|
| R 500 | 1 year 11 months | R 246 465 |
| R 1 000 | 3 years 6 months | R 433 646 |
| R 2 000 | 5 years 9 months | R 703 415 |
How the extra-payment calculation works
The calculator models the standard reducing-balance convention South African banks use for home loans: interest accrues monthly on the outstanding balance, your instalment settles that interest first, and the remainder reduces the principal. A once-off lump sum is credited against your balance in the first month, so every month after that charges interest on a smaller balance.
In shorten-the-term mode your instalment stays at its current level plus the extra amount, so the balance reaches zero sooner. In reduce-the-instalment mode you keep paying the extra, and after each month’s payments the bank recalculates your instalment on the reduced balance over the original remaining term — so your committed payment comes down while the term stays the same. The payoff is simulated month by month — including the final, smaller instalment — so the estimate is correct to the cent at the stated rate.
The rate is prefilled from the current prime lending rate of 10.5%, but you can move it to your actual rate — it is on your bond statement or your bank’s app.
Assumptions and methodology:
- Nominal annual interest rate compounded monthly (monthly rests), reducing balance — the standard South African home-loan convention.
- Monthly rate factor i = annual rate % ÷ 100 ÷ 12 (e.g. 10.50% → 0.00875 per month).
- Fixed annuity instalment: payment = P × i ÷ (1 − (1 + i)^−n), where P is the outstanding balance and n the remaining months.
- An extra payment reduces the principal in the same month it is made, immediately after the scheduled instalment. Interest the following month is charged on the reduced balance.
- In reduce-term mode the schedule ends when the balance reaches zero; the final payment is a smaller residual amount.
- In reduce-payment mode the instalment is recalculated after each extra payment over the remaining term at the unchanged rate. This models ideal bank behaviour — actual banks may only recalculate on request or at the annual rest date, so a real reduced instalment can lag the calculator.
- The calculation assumes the variable interest rate stays constant for the whole remaining term. Any future rate change alters both the scheduled instalment and the effect of extra payments.
- Keep full floating-point precision internally; round to the nearest rand only at display. Never round month-by-month balances or interest — that is how schedules drift off by rand amounts.
Rate basis: Current prime + 0.00pp margin (illustration assumes you are charged exactly prime). Prime is 10.5% (effective 2026-05-29, verified 2026-09-12 against South African Reserve Bank (SARB)). Actual bank rates differ per applicant and per bank.
These figures are illustrative, not a quote or an offer of finance. The pre-filled rate is the current prime lending rate of 10.50% as at 2026-09-12 (source: South African Reserve Bank (SARB)), and assumes you are charged exactly prime. Your actual rate depends on your credit profile, deposit and the bank’s assessment, and may be above or below prime — it differs for every applicant. The calculation assumes the interest rate stays constant for the whole remaining term, that every extra payment is applied to your bond in full in the month you make it, and that no fees or charges apply. Banks recalculate reduced instalments in their own way and on their own timing, so a real result can differ from this illustration. This calculator shows what could happen to a bond under these assumptions. It does not guarantee any saving, term reduction, reduced instalment or loan approval. Confirm the actual effect of an extra payment with your bank before relying on it.
Common questions
Is it worth paying extra into my bond?
Paying extra reduces the balance that interest is charged on, so it usually cuts both the term and the total interest you pay. Whether it is the best use of your spare cash depends on your situation — other expensive debt, emergency savings and whether you may need the money back. The calculator above shows the estimate for your actual balance, rate and term.
Should I reduce my term or my monthly instalment?
When you pay extra, most South African banks let you choose. Keeping your instalment the same and shortening the term saves the most interest, because you keep paying the higher amount. Asking the bank to recalculate your instalment down lowers your monthly commitment and frees cash flow, but saves less interest over the remaining term. You can switch between the two modes in the calculator to compare the estimates.
How much extra should I pay into my bond each month?
There is no single right number — even a modest extra amount compounds into meaningful interest savings over the years. The answer-first table under the calculator shows what R500, R1 000 and R2 000 extra per month would do at your current balance, rate and remaining term, so you can pick an amount that fits your budget.
Can I get my extra payments back if I need the money?
Only if your bond has an access facility (sometimes called an access bond) that lets you withdraw prepaid amounts, and only up to the limit your bank sets. Not every bond or bank offers this, and terms differ — read our guide to access bonds in South Africa before relying on it as an emergency fund.
Does my bank charge a fee for paying extra into my bond?
Banks handle this differently. Some charge a small administration fee when they recalculate your instalment or issue an early-settlement quote, and minimum prepayment amounts can apply. Ask your bank about its prepayment, recalculation and early-settlement fees before you pay in a large lump sum.
Related tools and guides
- Starting a new bond rather than paying extra on an existing one? Work out the monthly repayment with our bond calculator.
- Want the mechanics behind the numbers? Read our guide to paying extra into your bond — how the bank recalculates, which option to ask for, and the fees to check.
- Weighing up a better rate as well as extra payments? Work out whether refinancing is worth the switching costs with the break-even guide and calculator.
- Hoping to withdraw the extra again later? Understand how an access bond works in South Africa.