Spain Mortgage Calculator with Euribor: Payment and Interest

The Euribor (Euro Interbank Offered Rate) is the interest rate at which European banks lend money to each other. On variable-rate mortgages it is used as the reference index: the interest you pay is the Euribor plus a fixed percentage you agree with the bank, the spread (diferencial in Spanish). If the Euribor goes up, your interest rate goes up; if it falls, your rate falls.

The latest reading used by this calculator is the 12-month Euribor for October 2026 (3,239 %), taken from the Banco de España (Bank of Spain) page. It is only a starting value: the Euribor changes every month, so you can replace it with the one in your contract or with any value you want to simulate.

• Variable: the rate is the Euribor plus the spread and is reviewed periodically (usually every year or every six months). The payment can go up or down at each review.
• Fixed: the rate stays the same for the whole term. The payment does not change, in exchange for a starting rate that is usually different from that of a variable mortgage.
• Mixed: combines an initial period at a fixed rate with a later period at a variable rate.

The calculator has two modes: variable, where you add the Euribor and the spread, and fixed, where you type the rate directly. In both cases it holds the rate constant for the whole term, so for a mixed mortgage you can simulate each stage separately. Which type of mortgage suits you depends on your situation and on what the bank offers; this tool only calculates, it does not recommend.

The monthly payment follows the French amortization system: it is constant and combines interest and principal. With P as the loan amount, i as the annual rate divided by 100 and by 12, and n as the number of payments (years × 12):

payment = P × i / (1 − (1 + i)−n)

For example, for 200.000 € over 25 years (300 payments) at 3,00 % a year, the monthly rate is 3,00 % / 12 and the payment comes to 948,42 €. Multiplied by 300 payments, the total paid is 284.526,79 € and the interest adds up to 84.526,79 €. If the rate were 0 %, the payment would simply be the amount divided by the number of payments.

In each payment, one part covers the month’s interest (the outstanding debt times the monthly rate) and the rest reduces the principal. At the start the debt is high, so most of the payment is interest; over the years the split reverses. This is the yearly schedule for the example of 200.000 € over 25 years at 3,00 %, with selected years:

In the first year 5.925,39 € is paid in interest and 5.455,68 € of principal is repaid; the debt falls to 194.544,32 €. The calculator shows the full schedule, year by year, below the result.

These three examples use the same loan, 200.000 € over 25 years, and only the interest rate changes. This is the effect a rise or a fall in the Euribor has on the payment:

Going from 2,50 % to 4,00 % raises the payment from 897,23 € to 1.055,67 €, that is 158,44 € more a month, and the total interest from 69.170,04 € to 116.702,10 €. The last example in the table (150.000 € over 30 years at 3,50 %) gives a payment of 673,57 €.

Keep in mind that on a variable-rate mortgage the Euribor does not stay put: the payment at each review is recalculated with the debt outstanding at that moment and the new rate. The calculator assumes a constant rate, so it is useful for comparing scenarios, not for predicting the future.

The figure that surprises people most is the total interest. With 200.000 € over 25 years at 3,00 % you pay 84.526,79 € in interest on top of the principal, 42,26 % of the amount borrowed. A longer term reduces the monthly payment but increases the total interest, because the debt takes longer to come down; a shorter one does the opposite. With the calculator you can try different terms and compare both figures.

• Check that the payment fits your budget: compare it with your monthly net income, which you can estimate with the Spain net salary calculator.
• Simulate several rates: try a Euribor higher and lower than the current one to see how much the payment would change.
• Review the taxes on the purchase: buying a home carries taxes that this tool does not calculate; for transactions with IVA (Spanish VAT) use the Spain IVA (VAT) calculator.
• Think about your tax return: the mortgage may affect it depending on your case; estimate your IRPF (Spanish personal income tax) with the Spain IRPF and tax return calculator and consult a professional.
• Ask for a binding offer: the bank will give you the real payment with all the conditions; compare it with the simulation.

• It holds the interest rate constant for the whole term; on a variable-rate mortgage the real payment changes with each Euribor review.
• It does not include purchase costs, valuation, notary fees, fees charged by the bank, tied insurance or discounts on the spread.
• It does not cover early repayments or grace periods.
• The preloaded Euribor value is for October 2026; it is not today’s value. Replace it with the current one or with the one in your contract.
• It is an indicative tool and does not replace professional advice. Everything is calculated in your browser and no data is sent.

• Banco de España (Bank of Spain): Euribor

Informational content, not legal, accounting or financial advice. Always confirm with the official sources.