How this works
The capital-and-interest payment follows the annuity formula: payment = C × i ÷ (1 − (1+i)⁻ⁿ), where C is the capital still owed, n the number of months left and i the monthly rate — that is, the nominal annual rate divided by 12. The nominal rate is simply Euribor plus your spread. Since the spread is fixed in your contract, Euribor is what moves the payment. We compute the payment at today’s Euribor and at the new one, and show the difference. These numbers match Banco de Portugal’s official examples.
Frequently asked
Where do the pre-filled Euribor values come from?
They are indicative, just to start the simulation — do not treat them as your contract rate. Euribor changes every business day and your bank applies the average of one specific month. Replace the fields with the figure on your statement or rate-revision letter. Banco de Portugal publishes the official rates.
What is the spread and why doesn’t it change?
The spread is the bank’s margin added to Euribor, fixed in your contract (unless you renegotiate). Add it to Euribor to get the nominal annual rate that actually generates interest. If your contract says "6-month Euribor + 1.2%", the spread is 1.2%.
Does this include insurance and fees?
No. This tool computes only the capital-and-interest payment — the part that moves with Euribor. Life and home insurance, fees and taxes go into the APR (TAEG), not the base payment. For the APR and total cost, use Banco de Portugal’s official simulator.
Which term do I enter — the original or what’s left?
What’s left. To see how the next reset changes your payment, use the capital still owed and the years still remaining, not the figures from when the loan started. Both are on your loan statement.
Why doesn’t the payment fall in proportion to Euribor?
Because interest is only part of the payment. In an annuity, a 0.5-point drop in Euribor cuts the interest, but the capital you still repay stays the same. The effect also depends on the term left: the fewer years remain, the less interest weighs and the smaller the impact.
DISCLAIMER
Estimates the capital-and-interest payment only. It excludes insurance, fees, taxes and the APR, and ignores grace or deferral periods. The pre-filled Euribor is indicative — confirm the real value with your bank or Banco de Portugal. Not financial advice. For the loan’s total cost, use Banco de Portugal’s official simulator.