Mortgage amortization calculator

How the calculator works

Most German home loans are annuity loans (Annuitätendarlehen): you pay the same amount every month, and that amount covers the interest first and repays debt with the rest. Banks describe the payment with two percentages, the nominal rate (Sollzins) and the initial repayment rate (anfängliche Tilgung):

Monthly payment = (rate + initial repayment) × loan ÷ 12

Each month the calculator then works out:

1. Interest = remaining debt × rate ÷ 12, rounded to the cent, as banks charge it.
2. Repayment = payment − interest. Because the debt falls, the interest falls a little every month and the repayment share grows.
3. Extra repayments (Sondertilgung) are paid at the end of each loan year, up to the yearly allowance in your contract.
4. After the fixed-rate period (Zinsbindung) the same payment continues. By default the rate stays the same; under “Extra repayments and later rates” you can set a different one.

You can also enter the monthly payment you want, or the number of years in which the loan should be repaid; the calculator then works out the matching repayment rate. The result is the remaining debt at the end of the fixed rate, the total interest, the payoff date and the full schedule year by year.

We checked the arithmetic against a worked example from the German cooperative banks: €450,000 at 3 % with 3 % initial repayment and 15 years fixed. The calculator gives the same €2,250 monthly payment and the same remaining debt of €194,655.65, to the cent.

Example: €300,000 at 3.5 % with 2 % repayment

A €300,000 loan at 3.5% with 2% initial repayment costs €1,375.00 a month. In the first year €10,403 of the payments is interest and only €6,097 repays debt. After the 10-year fixed rate, €228,284 is still owed, 76% of the loan. If the rate then stays the same, the loan is repaid after 29 years, with €177,593 of interest in total.

The initial repayment rate matters more than most people expect:

Initial repayment	Monthly payment	Owed after 10 years	Paid off after
1 %	€1,125	€264,142	43 years 1 month
2 %	€1,375	€228,284	29 years
3 %	€1,625	€192,426	22 years 2 months

German consumer advisers (Verbraucherzentrale) recommend at least 2 %, better more, so that the debt left when the fixed rate ends is a size you can refinance even if rates have risen.

Repayment rate, monthly payment or term?

Pick the mode that matches the question you have. Initial repayment is how a bank’s offer is written, so use it to check an offer or compare two. Monthly payment starts from your budget: enter what you can pay, and the calculator shows the repayment rate it implies and how long the loan runs. Term works backwards from a date, such as being debt-free before retirement; the payment is the classic annuity that clears the loan in exactly that time if the rate stays the same. In all three, the schedule underneath is the same month-by-month calculation.

Extra repayments and the fixed-rate period

Most contracts let you repay extra each year without a fee, often 5 % of the original loan, sometimes 10 %. On the example loan, using the full 5 % (€15,000 a year) leaves €51,851 after 10 years and clears the debt after 12 years. Interest falls from €177,593 to €68,941. Whether that money would do more in an investment is a separate question; the overpay-or-invest calculator compares both with the same budget.

The rate after the fixed period is the biggest unknown. If it is 5.5 % instead of 3.5 %, the same payment repays less each month and the example loan runs for 36 years 1 month instead of 29 years. Under German law (§ 489 BGB) you can give notice on a fixed-rate loan ten years after receiving it in full, with six months’ notice and without an early repayment charge, which is one reason long fixed periods are common.

What the calculator can’t see

It knows one loan, not your household. It doesn’t include fees or insurance that make up the annual percentage rate (Effektivzins), it can’t know the rate you’ll be offered in ten years, and it doesn’t check whether the payment still fits when a child arrives, someone works part-time or one of you retires. The purchase costs on top of the price are in the home affordability calculator. Zenarios puts the loan into a month-by-month plan with your income, taxes, pension and the decisions still ahead.

Common questions

How is the monthly payment of a German mortgage calculated?

German banks quote an annuity loan (Annuitätendarlehen) by its nominal rate (Sollzins) and its initial repayment rate (anfängliche Tilgung). The monthly payment is (rate + initial repayment) × loan ÷ 12. A €300,000 loan at 3.5 % with 2 % initial repayment costs €1,375 a month. The payment stays the same; the interest share shrinks and the repayment share grows.

How much do I still owe after a 10-year fixed rate?

For that example €228,284, about 76 % of the loan. With 3 % initial repayment (€1,625 a month) it is €192,426; with 1 % (€1,125 a month) €264,142. Whatever is left has to be refinanced at the rate on offer when the fixed period ends.

How long does it take to pay off a mortgage?

At 3.5 % interest that stays the same: about 43 years with 1 % initial repayment, 29 years with 2 %, 22 years with 3 % and 18 years with 4 %. Every extra point of initial repayment saves years and a large part of the interest.

How much can I repay early?

During the fixed-rate period only what your contract allows. Many German lenders allow 5 % of the original loan a year, some 10 %. On the example loan, €15,000 a year (5 %) leaves €51,851 after 10 years and clears the loan after 12 years instead of 29.

What if the rate is higher after the fixed period?

The calculator keeps the monthly payment and changes only the split between interest and repayment. If the example's rate rises from 3.5 % to 5.5 % after 10 years, the loan runs about 36 years instead of 29. Turn on a different rate under “Extra repayments and later rates” to test your own figure.

Sources

• Volksbanken Raiffeisenbanken: Tilgungsplan erstellen (worked example)
• Verbraucherzentrale: Immobilienfinanzierung – diese Modelle gibt es
• Verbraucherzentrale: Baufinanzierung vorzeitig ablösen
• § 489 BGB: the borrower's right to terminate after ten years

By Constantin Metz, the maker of Zenarios · Reviewed 25 October 2026. Results are estimates from your inputs and simplified rules, not financial, tax or legal advice. How Zenarios calculates