Bond Repayment Calculator — South Africa
Calculate your exact monthly repayment, total interest and how extra payments cut years off your bond.
Quick answer: A South African bond is repaid through amortising monthly instalments that blend interest and capital. At the current prime rate of 10.50% (SARB, 28 May 2026), a R1,500,000 bond over 20 years costs approximately R14,976 per month, with early years weighted mostly toward interest.
Bond Repayment Calculator
Prime: 10.50% · Investor rate: typically prime + 0.5% to prime + 1.5%
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How to Use This Calculator
Enter the purchase price and your planned deposit — the calculator derives your loan amount automatically and shows your deposit as a percentage of the purchase price. Set the interest rate (use 11.00% for prime plus 0.5% if you have a strong credit profile) and select your bond term (20 years is standard for SA investment property bonds).
Add an extra monthly payment to see exactly how much interest you save and how many months come off your term — this is one of the most powerful financial levers available to SA property investors. The Investor Rental Offset panel shows the minimum monthly rental needed to cover your bond at break-even and at 110% (the SA bank coverage test).
How Bond Repayments Work in South Africa
A South African home loan — called a bond — works on an amortising repayment structure. This means each monthly payment covers both interest and a portion of the original loan (the principal). In the early years, most of your repayment goes toward interest. As the loan balance decreases, the interest portion shrinks and the principal portion grows.
The formula used to calculate your monthly repayment is: M = P × [r(1+r)^n] ÷ [(1+r)^n − 1] — where P is the loan amount, r is the monthly interest rate (annual rate divided by 12), and n is the number of monthly payments (years multiplied by 12). At the current prime rate of 10.50%, an investor paying prime plus 0.5% on a R1,500,000 bond over 20 years pays approximately R15,200 per month.
Why Extra Payments Are a Powerful Investor Strategy
Because SA bonds are front-loaded with interest, paying even a small extra amount each month has a disproportionate impact. Every rand of extra payment reduces your outstanding balance, which immediately reduces the interest charged the following month. This creates a compounding saving effect that accelerates over time.
On a R2,000,000 bond at 11.00% over 20 years, paying R1,500 extra per month saves approximately R380,000 in interest and cuts the term by almost 4 years. That freed-up equity can then be deployed as a deposit on a second investment property, creating a powerful property accumulation strategy without requiring additional income.
Most SA bond agreements allow extra payments into an access bond facility — meaning the money remains accessible in an emergency while still reducing your interest charge. Confirm this feature with your bank when signing your bond documents.
Bond Repayment Rates at 11.00% (Prime + 0.5%) — Reference Table
| Loan Amount | 20 Years | 25 Years | Total Interest (20yr) |
|---|---|---|---|
| R 800,000 | R 8,106 | R 7,510 | R 1,145,000 |
| R 1,000,000 | R 10,133 | R 9,387 | R 1,432,000 |
| R 1,500,000 | R 15,199 | R 14,081 | R 2,148,000 |
| R 2,000,000 | R 20,265 | R 18,774 | R 2,864,000 |
| R 2,500,000 | R 25,332 | R 23,468 | R 3,580,000 |
| R 3,000,000 | R 30,398 | R 28,161 | R 4,296,000 |
Rates calculated at 11.00% per annum. Actual repayments depend on your negotiated rate and bond structure.
20-Year vs 25-Year Bond: Which is Better for SA Investors?
The standard term for SA investment property bonds is 20 years. Most property investors who have run the numbers choose 20 years for a straightforward reason: the additional monthly cost over a 25-year term is modest, but the interest saving over the life of the bond is enormous.
On a R2,000,000 bond at 10.75%, a 25-year term saves approximately R1,500 per month versus 20 years. But the 25-year term costs an extra R540,000 in total interest over the life of the loan. Most SA investors regard that as an expensive way to lower a monthly commitment — particularly when the property should be generating rental income to cover most of the repayment anyway.
The practical rule: choose 20 years and use an access bond facility as your buffer. If cash gets tight, temporarily reducing your extra payment achieves the same effect as a longer term without the lifetime interest cost.
The SA Bank Rental Coverage Test
When SA banks assess investor bond applications, they apply a rental coverage test — the expected monthly rental income must cover at least 100–110% of the bond repayment. Some banks apply this as a standalone test; others fold it into the broader debt service ratio (DSR) assessment alongside your personal income.
The Investor Rental Offset panel in this calculator shows you the rental income required at 100%, 110%, and 125% coverage. A 125% coverage ratio means the property generates enough rental income to cover the bond repayment and have 25% left over for rates, levies, maintenance and vacancy — a useful threshold for identifying genuinely cash-positive investments at the current interest rate. Before committing, run your salary through PayTools to confirm your exact net monthly income — bond serviceability is assessed on take-home pay, not gross salary.
Manual Calculation — Working Out Your Own Bond Repayment
The bond repayment formula is M = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1], where P is the loan amount, r is the monthly interest rate, and n is the number of monthly payments. At the current prime rate of 10.50% (SARB, 28 May 2026), the monthly rate is 10.50% ÷ 12 = 0.875%. For a R1,500,000 bond over 20 years (240 months), this gives a monthly repayment of approximately R14,976. Extending the same bond to 25 years (300 months) drops the monthly repayment to roughly R14,163 — a saving of R813 a month — but total interest paid rises from around R2.09 million to R2.75 million over the life of the loan, an extra R654,650 in interest for the lower monthly instalment. Investors weighing this trade-off should model both terms against expected rental income and their own cash flow tolerance before committing to a 25-year structure purely to lower the monthly repayment.
Working out your bond costs? See where this fits in the complete SA Home Buyer's Guide →