Number format: this calculator uses German notation throughout — a comma is the decimal separator and a dot groups thousands. “1.234,56” means one thousand two hundred thirty-four euros and fifty-six cents. The figures come from German tax law, so they are shown the way German authorities write them.
Compounding period (Verzinsungsperiode)
How often per year interest is credited — the more often, the stronger the compounding.
In plain language
How often a year does the bank credit interest? Once a year, twice, every month? The more often, the more you get, because interest already credited earns interest itself. The difference is smaller than many expect — but it is there, and over twenty years it adds up. That is why offers always state the number of compounding dates too.
In detail
Under the commercial convention used here the nominal annual rate is spread evenly across the periods: the period rate is the annual rate divided by the number of periods. Because interest is credited at the end of each period and earns interest from then on, the effective annual yield exceeds the nominal rate — and the more often it is credited, the more clearly so. The limiting case of continuous compounding gives the highest value but differs only marginally from monthly. For comparing two offers the right figure is therefore not the nominal rate but the effective annual rate, which already contains the number of periods.
Worked example
10.000 € of starting capital at a nominal 4 % over ten years: credited annually, the capital grows to 14.802,44 €. Half-yearly it is 14.859,47 €, quarterly 14.888,64 €, monthly 14.908,33 €. Between annual and monthly there are therefore 105,89 € — about 1 % of the starting capital, from the rhythm of crediting alone.
In brief
The annual rate is spread over the periods; crediting during the year raises the effective annual yield.
Legal basis: commercial compound interest · as at 2026