Free lending tool
Loan affordability calculator
Every other calculator starts with a loan amount. This one starts with your payslip. Enter what you earn, what you spend and what you already repay, and it works backwards to the largest loan those numbers support — measured two ways, because lenders do not all use the same rule.
Your money each month
Before deductions — this is the figure the debt-to-income rule is measured against.
Rent, food, transport, school fees and anything deducted from your pay before it lands.
What you already pay each month on other loans, cards or store accounts.
The loan you want
The rules to test against
The share of gross income a lender will let total repayments reach. Most sit between 35% and 45%.
Percentage points added to the rate, to check the loan still works if borrowing gets dearer. Set to zero to skip.
Enter a figure to check it against what you can afford.
You could borrow up to
ZAR 179,794.45
ZAR 6,500.00 a month
The lower of the two rules below decides this figure.
- Affordable repayment
- ZAR 6,500.00
- Limited by
- Debt-to-income cap
- Maximum loan
- ZAR 179,794.45
- Number of payments
- 36
- Total you would repay
- ZAR 234,000.00
- Of which interest
- ZAR 54,205.55
- If rates rose to 20.00%
- ZAR 174,902.40
The two rules, side by side
Lenders do not all measure affordability the same way. The tighter rule is the one that decides your answer.
- Debt-to-income capBindingZAR 6,500.00
- ZAR 179,794.45
- Residual incomeZAR 9,500.00
- ZAR 262,776.50
An estimate for comparison. A lender runs its own affordability assessment against your bank statements and credit record, and its limits may be tighter than the ones set here.
What a longer term buys you
The same monthly budget stretched over different terms. A longer loan raises what you can borrow — and raises what it costs by a great deal more.
Opens in Excel, Sheets or any spreadsheet.
| Term | Payments | Maximum loan | Total repaid | Total interest |
|---|---|---|---|---|
| 6 months | 6 | ZAR 37,031.72 | ZAR 39,000.00 | ZAR 1,968.28 |
| 1 year | 12 | ZAR 70,898.78 | ZAR 78,000.00 | ZAR 7,101.22 |
| 2 years | 24 | ZAR 130,197.63 | ZAR 156,000.00 | ZAR 25,802.37 |
| 3 years | 36 | ZAR 179,794.45 | ZAR 234,000.00 | ZAR 54,205.55 |
| 4 years | 48 | ZAR 221,276.60 | ZAR 312,000.00 | ZAR 90,723.40 |
| 5 years | 60 | ZAR 255,971.75 | ZAR 390,000.00 | ZAR 134,028.25 |
| 7 years | 84 | ZAR 309,261.11 | ZAR 546,000.00 | ZAR 236,738.89 |
How affordability is actually measured
Two rules, one stress test, and a trade-off that catches most borrowers out.
- 1
Debt-to-income cap
The quickest test: total repayments, including the new loan, may not exceed a set share of gross income. It is easy to apply and easy to pass — which is its weakness, because it says nothing about what the household actually spends.
- 2
Residual income
What is genuinely left after living costs and existing repayments. South Africa’s National Credit Act requires an assessment of discretionary income, which is this rule rather than the first — and it catches a high earner with high outgoings that a debt-to-income cap would wave through.
- 3
A longer term is not free
Stretching the same repayment over more months raises the amount you can borrow, because more payments carry more principal. But interest accrues for longer on a balance that falls more slowly, so the total cost climbs far faster than the loan does.
- 4
The stress test
A loan that just fits today may not fit if rates rise. Re-running the same budget at a higher rate shows how much of the ceiling was resting on the rate staying put — and whether there is room to absorb an increase.
The three tests this tool applies
Each answers a different question, and a borrower has to pass all of them.
| Test | What it asks | How it is worked out |
|---|---|---|
| Debt-to-income cap | Would total repayments take too large a share of what you earn? | Gross income multiplied by the limit, less what you already repay each month. |
| Residual income | Is there enough left over once the bills are paid? | Income less living expenses less existing repayments. Whatever remains is what a new loan can use. |
| Rate stress test | Would the loan still work if borrowing got dearer? | The same affordable repayment re-priced at the rate plus the buffer, giving a lower ceiling. |
The binding rule is whichever leaves least. A borrower who passes the debt-to-income cap comfortably can still fail on residual income, and it is usually the residual test that a real lender applies to your bank statements.
Amortization Schedule GeneratorQuestions about loan affordability
- There is no single answer, which is why this tool shows two. A common underwriting cap puts total debt repayments at 35% to 45% of gross income. But the more meaningful test is what is actually left after your living costs — a 40% cap means very different things to two people with the same salary and different rent.
- Before deductions. The debt-to-income rule is conventionally measured on gross income, so that is what the field expects. Put your statutory deductions — tax, pension, medical aid — into the living expenses field along with rent and food, and the residual income rule will then be working from what genuinely reaches your account.
- Debt-to-income is a ratio: repayments as a share of what you earn. Residual income is an amount: what is left after everything else. The ratio is easier to compare across borrowers, the amount is closer to the truth. Neither is a superset of the other, so a borrower can pass one and fail the other — which is exactly what the comparison in this tool is for.
- Because affordability is a limit on the repayment, not on the loan. Spreading the same repayment over more payments carries more principal, so the ceiling rises. The catch is that interest accrues on the outstanding balance for longer, so the total cost rises much faster — stretching a loan from one year to five in the table below roughly quadruples what you can borrow and multiplies the interest many times over.
- It re-runs the same calculation at a higher rate, to see whether the loan would still be affordable if borrowing got dearer. It matters most on a long variable-rate loan, and matters little on a short fixed-rate one. If a two-point rise wipes out a large share of your ceiling, you were relying on the rate staying where it is.
- No. Affordability is one part of a credit decision. A lender also weighs your repayment history, how long you have been employed, what your bank statements show against what you declared, and its own appetite for risk. This tool tells you what the arithmetic allows, not what an underwriter will decide.
- Yes, substantially. On a flat rate, interest is charged on the original amount for the whole term regardless of what you have repaid, so the same monthly budget carries a noticeably smaller loan than it would on a reducing balance. Switch the interest method above to see the gap on your own figures.
- Use a conservative figure rather than an average — ideally close to your worst recent month. A repayment that only works in a good month is a repayment you will miss in a bad one, and lenders assessing irregular income generally do the same thing, taking a lower figure than the average and asking for several months of statements.
- No. The whole calculation runs in your browser, and the exports are generated on your own device. Nothing you type is sent to a server, saved, or logged, and there is no sign-up.
How much of my income can go towards loan repayments?
Should I enter my income before or after deductions?
What is the difference between debt-to-income and residual income?
Why does a longer term let me borrow more?
What is a stress test and do I need one?
Does this guarantee a lender will approve me?
Does the interest method change what I can borrow?
What if my income varies month to month?
Is my data stored?
Affordability checks built into origination
Lendbox captures income, expenses and existing obligations on the application itself, then applies your own affordability rules before a loan reaches approval — so the assessment is recorded against the file rather than worked out on a calculator and forgotten.
No credit card required.
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