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Calculadora Capital

Mortgage Payment Calculator (Portugal)

How much will the home loan cost you each month? This calculator estimates the monthly payment (prestação) from the amount borrowed, the rate (Euribor + spread) and the term, and shows the total paid and the interest over the life of the loan. Most usefully, it shows at a glance how much the payment rises or falls if Euribor moves by one percentage point.

The annual rate (TAN) is Euribor plus your contract spread. Euribor changes over time; the spread stays fixed. Check the current Euribor in the sources listed below.

Monthly payment
€673.57
TAN (Euribor + spread)
3.5%
Total interest
€92,484.13

If Euribor changes

Euribor +1 point
€760.03 (+€86.46)
Euribor −1 point
€592.68 (-€80.89)

Loan summary

Amount financed€150,000.00
TAN (Euribor 2.5% + spread 1.0%)3.5%
Number of payments360
Total paid (360 payments)€242,484.13
Of which interest€92,484.13

Educational estimate, not financial advice. It computes the capital-and-interest payment (French system) at the rate you choose; it excludes mandatory insurance, commissions and stamp duty, and the TAEG is higher than the TAN. Because Euribor is variable, the real payment changes at each reset.

What Euribor and the spread are

Almost every Portuguese mortgage is variable-rate: the annual interest rate (the TAN, nominal annual rate) is the sum of two parts: Euribor, a market index that rises and falls, and the spread, the fixed margin the bank adds, set in your contract. When Euribor moves, your payment moves; the spread stays. TAN = Euribor + spread.

How the payment is calculated

The loan is repaid in equal monthly instalments (the "French" amortisation system): each payment covers that month’s interest on the outstanding balance and repays the rest. The formula is payment = principal × i / (1 − (1 + i)^−n), where i is the monthly rate (the TAN divided by 12) and n is the number of months. Early on, most of the payment is interest; over time more and more of it repays capital.

Why the payment rises when Euribor rises

Because the rate is variable, a rise in Euribor lifts the TAN and, with it, the payment, and the effect is bigger on long terms and large amounts. That is why the calculator shows, next to the result, what you would pay if Euribor rose or fell by one percentage point: it is the quickest way to test how much headroom your budget has.

Worked example

On a €150,000 loan over 30 years, with Euribor at 2.5% and a 1.0% spread (a 3.5% TAN), the payment is about €673.57 a month. Over the 30 years you would pay about €242,484, of which €92,484 is interest. If Euribor rose by one point (to 3.5%, a 4.5% TAN) the payment would become €760.03, €86.46 more a month; if it fell by one point, it would drop to €592.68.

Frequently asked questions

How is the mortgage payment calculated?
The constant monthly payment is given by the amortisation (French-system) formula: payment = principal × i / (1 − (1 + i)^−n), where i is the monthly rate (the TAN ÷ 12) and n is the number of months in the term. This calculator applies that formula to the amount, the rate (Euribor + spread) and the term you enter.
What is the TAN and how does it relate to Euribor and the spread?
The TAN (nominal annual rate) is the interest rate charged on the outstanding balance. On a variable-rate loan it is the sum of Euribor (the market index, which changes) and the spread (the bank’s fixed margin). When Euribor rises or falls, the TAN, and the payment, follow; the spread stays fixed for the contract.
If Euribor rises, how much does my payment go up?
It depends on the outstanding amount and the remaining term, but the calculator shows the impact directly: next to the payment it lists what you would pay with Euribor +1 point and −1 point. The larger the balance and the longer the term, the bigger the increase per point.
Is this the full payment I will make to the bank?
No. This is the capital-and-interest payment. The actual instalment usually also includes the mandatory insurance (life and buildings) and any commissions. The total cost of the loan is measured by the TAEG, which bundles the spread, commissions, associated insurance, stamp duty and fees, always higher than the TAN.
Are the figures guaranteed?
No. It is an educational estimate at a fixed rate you choose. Because Euribor is variable, the real payment changes at each reset (usually every 6 or 12 months). It excludes insurance, commissions and taxes and is not financial advice.

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Sources

Author: Thorben Rasmus Idel · Reviewed by: Nahar Geva · Last reviewed: 2026-06-01