Debt-service ratio and borrowing capacity calculator
The new 45% limit from Banco de Portugal (central bank), the rate stress test, and the term capped by age — the maths the bank will do, worked out before you go in.
Household total: everything that lands in the account, after tax and social security.
Car, personal, credit cards — everything you already pay monthly counts towards the DSTI.
Sets the recommended maximum term: 40 years up to age 35; 35 years above that.
You can adjust it to match the reference rate in your own proposal.
The bank’s margin on your proposal.
Turn on to also apply the 90% loan-to-value cap (LTV, primary residence).
The bank can lend you up to
€206,663
Where this number comes from
| Recommendation ceiling — 45% of income | €1,125.00 |
|---|---|
| = Maximum test payment | €1,125.00 |
| Rate used in the stress test | 5.123% (TAN 3.623% + 1.5 pp shock) |
| Maximum principal under the DSTI, over 30 years | €206,663.22 |
| Maximum you can borrow | €206,663.22 |
| Estimated real payment (no shock) | €942.26 |
| Real debt-service ratiobetween 35% and 45% — banks look more closely | 37.7% |
Since 1 August 2026, Banco de Portugal recommends a maximum DSTI of 45% (previously 50%), calculated using the payment at a stressed rate. It’s a recommendation, not a ban: up to 10% of each bank’s new lending can exceed it, on an exceptional basis — the final decision is always the bank’s.
How the calculation works
The bank doesn’t ask how much you want to borrow — it asks how much you can afford in a bad month. Banco de Portugal’s macroprudential recommendation turns that into three tests: the sum of all loan payments must not exceed 45% of the household’s net income, the payment is simulated at a rate stressed by the term’s shock, and the term itself is capped by the age of the oldest borrower.
The calculator does the maths in the bank’s order: it applies the 45% to your income, deducts the payments you already make, stresses the rate with the shock (except on a fixed rate), and converts the remaining test payment into principal, over the effective term. If you turn on the property price, it also applies the 90% financing cap — whichever gives less is your maximum.
Important: it’s a recommendation, not a law. Each bank can exceed the limit on up to 10% of the new lending it grants, on an exceptional and justified basis — but since 1 August 2026 the margin is narrower, and most proposals will sit close to these numbers.
Once you know your maximum, the next step is the full tally of the money you need on the day of the deed — down payment, taxes, registrations — in the total purchase costs calculator, and the payment in detail, with the amortization table, in the mortgage payment calculator.