The 30% guideline
A common rule of thumb is that the bond repayment shouldn't be more than 30% of your gross monthly income. Old Mutual's home loan page states it in those words. The calculator takes 30% of your income, subtracts your other debt repayments, and works out the loan that repayment would cover at the rate and term you choose.
What banks actually look at
The National Credit Act makes every bank check that you can afford the loan, and the 30% is only a starting point. They also look at:
- your credit record and how you've repaid other debt
- your monthly living expenses
- how stable your income is (permanent, contract or self-employed)
- the property itself, which the bank values before it lends
That's why two banks can give the same person different answers. How banks decide.
Buying together
If you apply with a partner, both incomes count, and both people are responsible for the whole loan.
Questions people ask
How much salary do I need for a R1 million bond?
Using the 30% guideline at prime (10.75%) over 20 years, a gross income of about R33 841 a month.
How much can I borrow on R30,000 a month?
With no other debt, using the 30% guideline at prime over 30 years, about R964 133. The bank's own assessment decides.
Where this comes from
- Old Mutual: home loans (the 30% guideline) (read 11 Oct 2026)
- South African Reserve Bank, current market rates (policy rate 7.25%, prime 10.75%) (read 11 Oct 2026, figures dated 9 Oct 2026)
Checked October 2026.