Home Loan Affordability Calculator

Estimate the maximum bond you'd qualify for.

Reviewed by The QuickCalc Editorial Team · Last updated · About our methodology

Enter your details

Result

Estimated max bond
R1 107 310,31
Estimated instalment
R12 000,00

Inputs & results at a glance

Updates live as you change the form above.

ItemTypeValue
Gross incomeInputR40 000,00
ExpensesInputR8 000,00
RateInput11.75%
TermInput20 years
Max instalmentResultR12 000,00
Max bondResultR1 107 310,31

About this calculator

An affordability calculator estimates the maximum home loan you'd qualify for in South Africa given your income, monthly expenses, and current interest rates. Enter your gross monthly income, your total monthly expenses (excluding rent), the interest rate on offer and the loan term you're targeting, and the calculator returns the maximum bond principal you could support.

The maths follows what South African banks actually do. Banks generally cap the total bond instalment at around 30% of gross monthly income and total debt repayments at 40%. Since the National Credit Amendment Act, they must also run a full affordability assessment against your actual expenses. This calculator reverse-engineers the standard amortisation formula from a maximum monthly instalment you can afford.

The result is an estimate, not a pre-approval. For an official figure, apply for pre-qualification through a bond originator like ooba or BetterBond — the service is free to buyers, and they submit to multiple banks simultaneously. Add your deposit to the maximum loan amount to see the total purchase price you can target, and use our Transfer Duty Calculator to budget upfront costs.

How to use it

  1. 1Enter gross monthly income. Your total monthly income before tax.
  2. 2Enter monthly expenses. Total monthly expenses excluding your future bond.
  3. 3Enter interest rate and term. Use the current prime rate and a 20-year term as defaults.
  4. 4Read your maximum bond. The largest loan the standard affordability rule supports.

How it works

The calculator applies the standard South African bank rule that your bond instalment should not exceed roughly 30% of gross monthly income, after considering your other monthly expenses. It calculates your maximum affordable monthly instalment, then reverse-engineers the amortisation formula to find the largest loan principal that produces that instalment at the interest rate and term you entered.

Real bank affordability assessments go further than this and consider your actual credit profile, existing debt commitments and disposable income analysis under the National Credit Amendment Act. For an official pre-approval, apply through a bond originator like ooba or BetterBond — the service is free and they submit to multiple banks at once.

Formula

Max instalment ≈ 30% × Gross income − Existing debt; Max loan = Max instalment × [(1+r)ⁿ − 1] / [r(1+r)ⁿ]

r = monthly rate (annual ÷ 12); n = months (years × 12); the second formula is the amortisation formula solved for principal.

Worked examples

R40,000 gross income, R8,000 expenses, 11.75% over 20 years

Max instalment ≈ R12,000. Max loan ≈ R1.11m.

R70,000 gross income, R15,000 expenses, 11.75% over 20 years

Max instalment ≈ R21,000. Max loan ≈ R1.95m.

Frequently asked questions

What's the rule banks use?

South African banks generally limit the total instalment on your bond to about 30% of your gross monthly income, and total debt repayments to about 40%.

Does the bank consider my expenses?

Yes — since the Credit Amendment Act, banks must run an affordability assessment using your actual expenses, not just income.

What deposit does the calculator assume?

None. The figure shown is the maximum bond principal supportable by your net affordability, before any deposit is added to reach a purchase price.

How accurate is this vs a bank pre-approval?

It's a solid estimate. For an official figure, apply for pre-qualification with a bond originator like ooba or BetterBond.

What interest rate should I enter?

Use the current prime rate (around 11.75%) as a realistic default. If your credit score is strong you may qualify slightly below prime.

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