What you can realistically borrow — and whether you could still pay if rates rose.
Uses the debt-to-income method lenders actually apply. Works in any currency.
Almost every lender in the world applies some version of the same three tests. The binding one is usually debt-to-income.
Your total monthly debt payments — the new mortgage plus car finance, credit cards and personal loans — must stay under a percentage of gross monthly income. Common limits:
| Market / product | Typical maximum DTI |
|---|---|
| Conservative / conforming | 36% |
| US qualified mortgage | 43% |
| Many GCC banks | 50% of salary (regulator-capped) |
| UK affordability model | Income multiple ~4.5× plus a stress test |
Enter the limit that applies to you. Using a lower figure than the maximum is how you leave yourself room.
The deposit does not affect the monthly payment maths — it raises the price you can reach, one-for-one. It also drives the rate you are offered: most lenders price in tiers at 90%, 80% and 75% loan-to-value, and a larger deposit often removes mortgage insurance entirely.
Regulators in the UK, EU, Canada and Australia require lenders to check you could still pay if rates rose by roughly two percentage points. This calculator runs that test for you. If the stressed maximum is far below the headline maximum, borrowing the full amount is a bet on rates staying low.
Usually not. The maximum is the point at which a lender still expects to be repaid, not the point at which your life stays comfortable. The stress-test figure is a better guide to a safe borrowing level.
It reduces the amount borrowed, so yes. It also commonly unlocks a lower rate band and can remove mortgage insurance, so the effect is larger than the headline number suggests.
Contractual monthly commitments: car finance, personal loans, student loans, credit-card minimums and any maintenance orders. Ordinary living costs like groceries and utilities are not counted in DTI, though lenders assess them separately.
Because they vary enormously by country — some markets bundle them into the payment, others bill them annually and some have none at all. Deduct your local figure from the available-for-mortgage line for a stricter result.
A regulator-permitted ceiling is a limit on the lender, not a recommendation for you. At 50% DTI, half your gross income is committed before tax, housing costs and savings — most household budgets get very fragile there.