Why is 21 written as einundzwanzig?

German puts the unit before the ten and joins them with und, so 21 is "ein-und-zwanzig" (one-and-twenty). Numbers below a million are written as one long word.

How large a number can I convert?

Up to 12 digits in the integer part, covering values into the billions (Milliarden). Million and Milliarde are written as separate words and pluralised correctly.

Is anything sent to a server?

No. The conversion runs entirely in your browser — no number you type ever leaves your device.

Number to Words in German

Spell any number in German words — instantly, in your browser.

Number to words in German

Type any whole number and see it spelled out in German words. German joins the unit and the ten with und (so 21 is einundzwanzig) and writes everything below a million as a single concatenated word, such as dreihundertfünfundvierzig.

Everything happens in your browser. Nothing you type is uploaded anywhere.