How the mortgage comparison works
This free tool compares up to ten mortgages at once using the French repayment system, commonly used for mortgages in Spain. Enter the loan amount, term in years, nominal interest rate and costs to see the monthly payment, total interest, estimated APR and overall cost of each option instantly.
What is the French repayment system?
Under the French repayment system, you pay a fixed monthly instalment throughout the loan term. Its composition changes each month: initially, most of the payment covers interest and only a small part repays capital; over time, that proportion reverses and more capital is repaid. It is the method used by most Spanish lenders for fixed-rate mortgages.
The monthly payment is calculated using this formula, where C is the principal, i is the monthly interest rate (the annual nominal rate divided by 12), and n is the number of months:
If the interest rate is 0%, the payment is simply the principal divided by the number of months.
What is APR and why does it differ from the nominal rate?
The nominal interest rate (TIN in Spanish mortgage documents) is the percentage the lender applies to the outstanding principal. The APR (TAE in Spain) is more comprehensive: it reflects the annualised cost of the loan by including monthly compounding and associated costs, such as fees, certain linked insurance products and eligible upfront costs.
The APR is normally equal to or higher than the nominal rate and is the more useful figure for comparing mortgages. Two loans with the same nominal rate can have very different APRs if one carries higher costs. This calculator estimates APR by solving the internal rate of return (IRR) of the actual monthly cash flows, matching payments and selected costs against the net amount received.
Upfront and recurring costs
The calculator separates several types of cost to produce a realistic comparison:
- Upfront costs included in APR: arrangement fees, formalisation costs or other loan-related charges that regulations include in the APR calculation.
- Other upfront costs: one-off costs that are not included in APR, such as a valuation you would have paid for anyway.
- Recurring costs: home insurance, life insurance, service charges and similar expenses. Enter the amount, choose monthly or yearly frequency, and decide whether each cost should be included in APR.
Figures calculated
- Monthly mortgage payment: the fixed mortgage payment before extras.
- Average recurring payment: the mortgage payment plus the monthly equivalent of recurring costs.
- Average monthly cost: also spreads upfront costs across the full loan term.
- Estimated APR: the annualised cost of the loan.
- Total interest and total mortgage payments: the interest paid and the sum of all mortgage instalments.
- Overall cost: mortgage payments, recurring costs and upfront costs over the full term. This is the figure used to identify the cheapest option.
Frequently asked questions
Are the calculations exact?
The formulas follow the standard French repayment system and calculate APR from the IRR. The result is still an estimate: your lender may apply different rounding, fees or linked products. Always use the lender's binding offer, such as the Spanish FEIN, for the definitive figures.
Can I use it for variable-rate mortgages?
The comparison assumes a fixed interest rate for the full term. For variable-rate mortgages, such as Euribor plus a margin, you can enter an expected rate as an approximation, but the actual payment will change at each review.
Does it store my data?
All calculations take place in your browser and no figures are sent to a server. To preserve your work after a reload, the figures you enter and your theme preference are stored in your browser's local storage. They never leave your device and you can delete them at any time with the “Start over” button.
Notice: this calculator is provided for information and educational purposes. It is not financial advice or a loan offer. Before taking out a mortgage, check the lender's official terms and seek independent financial advice if needed.