How the bond affordability calculator works
Last updated 9 November 2026
Before you start house hunting, it helps to know roughly what price range to look in. This calculator gives you that first estimate from your income, using a rule of thumb that many South African banks start from: your bond instalment should be no more than 30% of your gross monthly income.
It works backwards. First it takes 30% of your gross income as the most you could pay each month. Then it works out the biggest bond that instalment would repay over your chosen term at your interest rate. Your deposit is added on top to give the highest price you could pay. Finally it works out the transfer duty you would owe on that price.
This is a rule of thumb, not a bank decision. Under the National Credit Act, a bank runs a full affordability assessment before it approves a bond. That looks at your net income after tax, your living expenses, your other debts and your credit record, so the bond you are offered can be higher or lower than this estimate.
Worked example
Say you earn R 40 000 a month before tax, with no other debt and no deposit. These are the calculator’s starting values.
- The most you could pay each month is 30% of R 40 000, which is R 12 000.
- At the prime rate of 10.75% over 20 years, that instalment repays a bond of R 1 181 999.
- With no deposit, the most you could pay for a home is R 1 181 999. Homes up to R 1 210 000 pay no transfer duty, so there is none here.
- With a R 200 000 deposit, the price goes up to R 1 381 999, and transfer duty on that price is R 5 160.
If you also pay R 5 000 a month on other debt, your debt repayments would come to 42.5% of your income. Above 40%, the calculator warns that banks may approve less because of your other debt.
What the figures mean
- Maximum property price is the biggest bond the instalment supports, plus your deposit.
- Maximum bond is the loan amount your instalment would repay over the term.
- Maximum monthly instalment is 30% of your gross monthly income.
- Transfer duty is the tax you pay to SARS when you buy a property. It is paid in cash on top of the price. Work it out in detail with the transfer duty calculator.
- Debt repayments as a share of income adds your other monthly debt repayments to the new bond instalment and compares the total with your gross income.
Things to watch
- Rates change. A one-point rise to 11.75% cuts the maximum price in the example to R 1 107 310, which is R 74 689 less. The chart above shows this for your own figures.
- Upfront costs come on top of the price: transfer duty, transfer and bond attorney fees, and Deeds Office fees. These are paid in cash, on top of any deposit.
- A bigger deposit can lower your rate, because many banks charge less when you borrow a smaller share of the price.
- Owning a home costs more than the bond. Budget for rates and taxes, levies, insurance and maintenance.
- Once you have a price in mind, use the bond repayment calculator to see the total interest and what paying extra would save.
Sources
The prime rate of 10.75% applies from 25 September 2026. Transfer duty uses the SARS rates for the 2026/27 tax year. The 30% instalment guideline is a common banking rule of thumb, not an official limit. All figures were last checked on 9 November 2026, and the full list of sources is at the bottom of this page.