Bond Affordability Calculator
Find out how much home you can afford in South Africa — based on your income, expenses and current interest rates
Estimates based on the 30% DTI rule used by SA banks. Actual approval depends on credit score.
Three levels of detail — pick yours
Income, expenses, debts, rate, term — instant maximum property price with DTI rating.
Budget donut chart, bank DTI comparison, what-if income/deposit/rate sliders, joint application calculator.
Full NCA income breakdown, expense categorisation, credit score impact, rate × term sensitivity matrix.
Understanding Bond Affordability DTI rule • NCA • Example
How South African Banks Assess Affordability
South African banks use the National Credit Act (NCA) affordability assessment to determine your maximum bond. The primary measure is your Debt-to-Income (DTI) ratio — your total monthly debt obligations as a percentage of your gross monthly income.
The standard guideline is that your total debt repayments (including the new bond) should not exceed 30% of your gross monthly income. Banks also consider residual income — what is left after all expenses are paid.
The Affordability Formula
Where:
- The 30% rule is the primary bank DTI cap on gross income
- The residual income test (80% buffer) ensures enough cash flow remains after all expenses
- Banks use the lower of the two as the maximum affordable payment
Worked Example
Naledi earns R55,000/month gross. Her expenses are R18,000/month and she has R4,000 in other debt payments. She applies at the current prime rate of 10.25% over 20 years.
30% rule cap: R55,000 × 30% = R16,500/month
Residual test: (R55,000 − R18,000 − R4,000) × 80% = R26,400/month
Maximum affordable bond payment: R16,500/month (lower figure)
Using the PMT formula in reverse (at 10.25%, 20 years), this gives a maximum bond of approximately R1,635,000. With a 10% deposit she can afford a property up to approximately R1,800,000.
Frequently Asked Questions
How much income do I need to qualify for a bond in South Africa?
As a rough guide, you need a gross monthly income of at least 3× your desired monthly bond payment (based on the 30% DTI rule). For a R1,400,000 bond at 10.25% over 20 years, the monthly payment is approximately R13,830 — so you need at least R46,100/month gross income.
Living expenses and existing debts reduce what the bank will lend you. Use Tier 1 above to get a precise figure based on your actual income and expenses.
What is the 30% DTI rule and how do banks apply it?
The Debt-to-Income (DTI) ratio is the percentage of your gross monthly income that goes toward debt repayments. South African banks typically cap this at 30% for home loans under NCA guidelines.
For example: if you earn R50,000/month, banks will generally approve a combined debt obligation of no more than R15,000/month. Capitec may allow up to 35% for top-tier clients; FNB and Standard Bank are stricter at 30%.
Does a joint application significantly increase what I can afford?
Yes — a joint application combines both applicants' incomes, which directly increases the 30% income cap. If you earn R40,000 and your partner earns R35,000, your combined qualifying income is R75,000.
Use the Compare with Partner tab in the Extended Calculator above to model this precisely. Note that both credit records are assessed.
How does my credit score affect the interest rate I receive?
Your credit score directly affects the rate margin added to prime:
- Excellent (780+): Prime or prime minus 0.5% possible
- Good (670–779): Prime rate (currently 10.25%)
- Fair (580–669): Prime + 0.5% to prime + 1%
- Poor (below 580): Prime + 1% to prime + 2%, or declined
A 1% higher rate on a R1.2M bond over 20 years costs approximately R160,000 extra in interest.
What expenses should I include in the affordability calculation?
Under NCA affordability rules, banks consider all regular monthly obligations: food, transport, insurance, utilities, school fees, entertainment, medical aid, and clothing.
Do not include your current rent — this is replaced by your bond payment. Do not include the proposed bond payment itself — this is added separately. The Professional tier above allows full expense categorisation per NCA requirements.