A unique sequence of digits that identifies a bank account. Today in Europe, it is usually part of the IBAN (International Bank Account Number).
example
Für eine Online-Überweisung müssen Sie die Kontonummer des Empfängers eingeben.
For an online transfer, you have to enter the recipient's account number.
Usage tips
Compound word
The word is clearly made up of 'das Konto' (the account) and 'die Nummer' (the number). So it is literally the number that belongs to a bank account.
EXAMPLE
Bitte schreiben Sie Ihre Kontonummer deutlich lesbar auf das Formular.
Please write your account number clearly and legibly on the form.
Typical verbs
In connection with transfers and forms, an account number is often 'angegeben' (provided), 'eingegeben' (entered), 'benötigt' (needed), or 'geprüft' (checked).
EXAMPLE
Ich muss kurz meine Kontonummer nachschauen, bevor ich das Formular ausfülle.
I need to quickly look up my account number before I fill out the form.
Context: IBAN
In Europe, the account number is now part of the IBAN. In everyday language, people often simply say 'Kontonummer' (account number), even when they mean the entire IBAN.
EXAMPLE
Kannst du mir deine Kontonummer für die Miete schicken?
Can you send me your account number for the rent?
Common abbreviation
In written documents, especially on forms, 'Kontonummer' (account number) is very often abbreviated as 'Kto.-Nr.'
EXAMPLE
Tragen Sie bitte Ihre Kto.-Nr. in das dafür vorgesehene Feld ein.
Please enter your account number in the field provided.