How this works
A mortgage payment follows the annuity (French) formula: M = P·r / (1 − (1+r)⁻ⁿ), where P is the borrowed capital, r is the monthly interest rate (annual TAN ÷ 12) and n is the number of months. On a variable-rate loan the TAN is the Euribor plus the bank’s spread. Because the Euribor changes daily, I kept it as an editable field: enter today’s value and your spread, or switch to direct-TAN mode for a fixed rate. Everything runs in your browser.
Frequently asked
Is this the exact payment my bank will charge?
It is the capital-plus-interest part — the core of the payment. The bank’s real instalment almost always adds the required insurance (life and home multi-risk) and, in some contracts, fees or an account-keeping charge. For the figure to the cent, ask the bank for the FINE (the European Standardised Information Sheet). This tool gives you the baseline to compare offers fairly.
Why isn’t the Euribor fixed in the tool?
Because it changes every business day. Leaving it fixed would give wrong numbers tomorrow. I prefilled the 6-month Euribor with an indicative value from 24 June 2026 (≈ 2.63%), but check the day’s rate at Banco de Portugal and adjust the field. The spread, by contrast, is fixed in your contract and negotiated with the bank.
What is the difference between TAN and TAEG (APRC)?
The TAN (nominal annual rate) is Euribor + spread and is what feeds this formula to get the instalment. The TAEG (the APRC, effective overall annual rate) also includes insurance, fees and other costs — it is the figure to compare total cost across banks. This tool computes the instalment from the TAN; it does not compute the TAEG, which depends on each offer’s actual charges.
What happens to my payment if the Euribor rises?
On a variable-rate loan the instalment is reset periodically (every 3, 6 or 12 months, depending on the index). If the Euribor rises, the TAN rises and so does the payment. You can test this here: bump the Euribor field by 1 or 2 points and see the new instalment. It is the most honest way to gauge your safety margin before signing.
Can I use this for a fixed rate instead of a variable one?
Yes. Switch to “Direct TAN” mode and enter the fixed rate the bank quotes you (say 3.2%). The instalment formula is identical; only how you arrive at the TAN changes. In variable mode the TAN is Euribor + spread; in direct mode it is whatever number you type.
DISCLAIMER
Capital-and-interest estimate only. The bank’s real instalment usually includes required insurance (life and multi-risk) and may include fees, none of which are accounted for here. The prefilled Euribor is indicative (24 Jun 2026) — always confirm the day’s rate. For the exact figure and the TAEG/APRC, ask the bank for the FINE. Not financial advice.