How the monthly payment works
On a variable-rate Portuguese mortgage, your rate is the sum of Euribor (which the bank doesn't control and changes over time) plus the spread (the bank's margin, fixed in the contract). The payment is calculated on that total rate and the term. When Euribor rises or falls, the payment follows at each review.
Spread and term matter a lot
On the €200,000 example below, cutting the spread by 0.25 points — from 1.00% to 0.75% — drops the payment from €898.09 to €870.41 a month and saves €9,963.63 in interest over 30 years. Stretching the term the other way, from 20 to 30 years, cuts the payment from €1,159.92 to €898.09 but adds €44,931.52 in interest. Compare banks on the spread, and compare terms on the total, not just the monthly figure.
Worked example: €200,000 over 30 years
Take a €200,000 loan over 30 years with Euribor at 2.50% and a bank spread of 1.00%. The total rate, the TAN, is 2.50 + 1.00 = 3.50%. The monthly rate is 3.50 ÷ 100 ÷ 12 = 0.0029167, and the number of payments is 30 × 12 = 360. The monthly payment is 200,000 × 0.0029167 ÷ (1 − (1 + 0.0029167) to the power −360) = €898.09. Over the full term you repay €898.09 × 360 = €323,312.18, of which €323,312.18 − €200,000 = €123,312.18 is interest. That interest figure is the real cost of the loan, and it is why the calculator shows it next to the monthly payment: two loans with similar monthly payments can hide very different totals, and the total is what you actually hand over.
| Term | Monthly payment | Total repaid | Total interest |
|---|---|---|---|
| 20 years | €1,159.92 | €278,380.66 | €78,380.66 |
| 25 years | €1,001.25 | €300,374.14 | €100,374.14 |
| 30 years | €898.09 | €323,312.18 | €123,312.18 |
The table uses the same €200,000 loan and the same 3.50% rate, changing only the term. Stretching from 20 to 30 years cuts the monthly payment by €1,159.92 − €898.09 = €261.83, but adds €123,312.18 − €78,380.66 = €44,931.52 in interest. A longer term buys a lower monthly payment with a much higher total cost, and the trade is not close: ten extra years of payments cost nearly €45,000 on this loan. Borrowers who can afford the 20-year payment keep almost a third of the interest, which is why the term decision deserves as much attention as the rate.
Fixed rate, worked the same way
The page explains that you simulate a fixed rate by setting Euribor to 0 and putting the fixed rate in the spread field. A 3.00% fixed rate on the same €200,000 over 30 years gives a monthly payment of €843.21, a total of €303,554.90 and interest of €103,554.90 — €54.88 a month less than the 3.50% variable example, and €19,757.28 less interest over the term. The trade-off runs the other way too: a fixed rate does not fall if Euribor falls, so if variable rates dropped below 3.00% later, the fixed borrower would keep paying 3.00% while the variable borrower paid less. Fixed buys certainty; variable buys the chance of cheaper payments and the risk of dearer ones.
What a 1-point Euribor rise does
On a variable-rate loan, the payment follows Euribor at each review: the rate becomes the new Euribor plus your fixed spread, and the payment is recalculated on the remaining term. On the €200,000 example, if Euribor rose one point so the total rate went from 3.50% to 4.50%, the monthly payment would rise from €898.09 to €1,013.37 — €115.28 more every month. Over a year that is €1,383.36 of extra payments, which is why the page warns to update the Euribor field with the current rate before trusting an estimate. A borrower choosing between banks should also weigh the spread the same way: on this loan, a spread of 0.75% instead of 1.00% (a total rate of 3.25% rather than 3.50%) gives a monthly payment of €870.41 instead of €898.09, saving €27.68 a month and €9,963.63 in interest over 30 years. Small differences in the spread, negotiated once, pay out for decades.
What this estimate leaves out
The calculator covers the loan payment only. It does not include life or home insurance, bank fees, taxes or the APRC, which is why the page tells you to always request the official simulation, the FINE, from the bank before deciding. The FINE is the document that puts the full cost on the table in a standard format, including the charges this estimate skips. Use this calculator to compare terms, rates and spreads across banks, and use the FINE to confirm the final offer. Euribor itself deserves one more note: the page reminds you it changes daily, and that you should update it with the current 6- or 12-month rate. An estimate built on last month's Euribor is an estimate of last month's loan, not today's.
Frequently asked questions
Should I choose a fixed or variable rate?
Fixed gives predictability; variable can be cheaper but moves with Euribor. To simulate a fixed rate, set Euribor to 0 and use the fixed rate in the spread field. On the €200,000, 30-year example, a 3.00% fixed rate gives €843.21 a month and €103,554.90 in interest, against €898.09 and €123,312.18 at the 3.50% variable rate — €54.88 a month and €19,757.28 less interest. The catch runs the other way too: a fixed rate does not fall if Euribor falls.
What happens to my payment when Euribor moves?
On a variable-rate loan, the payment follows Euribor at each review: the rate becomes the new Euribor plus your fixed spread, and the payment is recalculated on the remaining term. On the €200,000 example above, if Euribor rose one point so the total rate went from 3.50% to 4.50%, the monthly payment would rise from €898.09 to €1,013.37 — €115.28 more a month. That is why the page warns to update the Euribor field with the current rate before trusting an estimate.
Does this include insurance and fees?
No. The estimate covers the loan payment only. It does not include life or home insurance, bank fees, taxes or the APRC, which is why the page tells you to always request the official simulation (FINE) from the bank before deciding. Use this calculator to compare terms and rates, not as a final offer.
Is a lower spread or a shorter term the better saving?
Both help, but the term usually matters more. On the €200,000 example, cutting the spread by 0.25 points saves €9,963.63 in interest over 30 years, while cutting the term from 30 to 20 years saves €44,931.52. If you can afford the higher monthly payment, shortening the term is the bigger win; if you cannot, negotiating the spread is the saving you can actually take.