Mortgage loan simulator: payment and total cost guide

Calculate your payment in Monetra's mortgage loan simulator before reading the detailed guide. Keep the results open so you can connect each input to the explanations below.

A mortgage loan simulator converts a purchase price and financing assumptions into comparable figures: total acquisition cost, principal borrowed, monthly payment, insurance, cumulative interest and remaining balance. Its best use is scenario analysis. It does not assess legal eligibility, affordability under a lender's policy or the probability that an application will be approved.

The model first calculates acquisition cost from the property price, agency-fee percentage and acquisition-fee percentage. It then subtracts the down payment to obtain the loan principal. A €200,000 property with a €40,000 down payment does not automatically produce a €160,000 mortgage because transaction costs may also need funding.

Loan payment and interest

For a positive rate, Monetra applies the fixed-payment amortizing-loan formula. Each payment before insurance contains more interest near the start and more principal near the end. The entered rate is a nominal annual rate divided by twelve for the monthly schedule.

Term has two effects. Extending it usually lowers the payment by spreading principal across more months, while increasing cumulative interest. Shortening it normally raises the payment and lowers borrowing cost. Compare both figures rather than optimizing one in isolation.

Two borrower-insurance bases

“Initial principal” produces a constant monthly premium based on the amount borrowed at origination. “Remaining principal” makes insurance decline as the balance falls. In the latter mode, the engine incorporates the insurance rate into the amortized payment and displays its first-month component; later insurance amounts decrease in the schedule.

This is useful for comparing calculation bases, but it cannot reproduce every insurer's pricing. Age bands, insured share, coverage, exclusions, medical loadings and stepped premiums are outside the model.

Start with the most certain purchase figures, then create variants for the financing terms that remain negotiable.

• Property price: use the expected transaction price, not the upper limit of your search budget.
• Agency fees: enter the percentage only when those fees are additional to the price used.
• Acquisition fees: supply your own percentage estimate; Monetra does not determine the legally exact amount.
• Down payment: include cash you can genuinely commit after protecting an emergency reserve.
• Term and nominal rate: take both from the same lender scenario so that comparisons remain consistent.
• Insurance: enter an annual rate and choose the calculation basis corresponding to the quote.

The down payment is capped at total acquisition cost, so principal never becomes negative. Renovation, guarantee, application, broker and other closing costs have no dedicated inputs. Account for them separately or adjust the project cost cautiously.

Assume a property price of €200,000, agency fees of 6%, acquisition fees of 8% and a €40,000 down payment. Financing lasts 20 years at a 3.40% nominal rate, with insurance at 0.15% of initial principal.

Simulated acquisition cost is €228,000, producing a €188,000 loan. Monetra estimates:

• a loan payment before insurance of about €1,081 per month;
• monthly insurance of €23.50;
• a first total payment of roughly €1,104;
• about €71,365 of interest and €5,640 of insurance over twenty years;
• a total financing cost near €77,005.

After year one, remaining principal is still about €181,320. After ten years, roughly €109,806 remains. This difference illustrates amortization: interest consumes a meaningful share of early payments, while principal repayment accelerates later.

Figures are rounded and follow only the stated assumptions. Costs absent from the model remain absent from the result.

The total monthly payment answers a cash-budget question. It is not sufficient for choosing between mortgages. Also compare total financing cost, which combines interest and insurance, and total paid, which adds those costs to the principal repaid.

The annual amortization table separates principal, interest and insurance. It can help estimate the debt at a possible sale date, but it does not calculate an exact early-redemption statement, which may include contractual charges or different day-count rules.

The chart makes time visible. If two scenarios have similar payments, faster amortization or a lower total cost may be attractive, provided the monthly commitment remains compatible with your full household budget.

Avoid changing every input at once. Keep a central scenario and alter one lever:

1. Term: compare, for example, 20 and 25 years using the same principal, rate and insurance basis.
2. Rate: add 0.5 percentage point to measure sensitivity before receiving a binding offer.
3. Down payment: test a smaller contribution that preserves cash reserves, then observe the extra payment and interest.

If your project uses several credit lines, a French PTZ or a delayed start, continue with the multi-loan simulator guide. To analyze a furnished rental after financing, read the LMNP profitability guide. For a primary residence, the buy, rent and ETF comparison places the loan inside a broader net-worth model.

Monetra provides an educational fixed-payment projection. It does not replace the APR or equivalent mandatory disclosure that combines required costs under applicable rules, nor the lender's contractual schedule. Variable rates, bridging interest, multi-loan smoothing, payment holidays, payment modulation, penalties, guarantees and application fees are not modeled.

Compare the scenario with the formal offer, your full spending plan and a safety margin. A manageable payment today can become difficult after an income shock or major expense. The purpose of simulation is not to discover one perfect number, but to identify which assumptions make the purchase robust and which make it fragile.