This question was motivated by a discussion at https://hsm.stackexchange.com/a/6949/1697.

In a Wikipedia entry on Planck's constant h I read the phrase

"die Bestimmung der Planckschen Konstanten h".

A similar phrase appears elsewhere. My question: Why does "Konstanten" have a final n? Google translates "the determination of Planck's constant" as "die Bestimmung der Planckschen Konstante", without the final n.

The issue is of some relevance for the cited discussion, because in a 1912 paper Einstein writes "Einführung der Planckschen Konstanten" and we're trying to determine whether "Konstanten" is singular (genitive) or plural (which it could be if Einstein is referring both to h and to another constant that today is called "Boltzmann's constant").

  • 1
    Note that your mentioned Wikipedia entry states in the first sentence of the article clearly "die Planck-Konstante h", so it is sure singular.
    – IQV
    Commented Jan 30, 2018 at 9:43
  • Are you sure he didn't say die Planck'sche Konstanze and meant his colleague's daughter? Commented Jan 30, 2018 at 14:10
  • It is a Genetiv of a Plural. German is very funny in this sense, you will see that 4x4 tables until you live. You have to learn not only their synthesis (singular/plural, gender, case -> artikel), but also the other direction: if you hear an artikel, you have to understand on the spot! I.e. if you are talking with a living German, you have roughly 0.1 seconds to decide, what is he using in any of his artikels. Btw, they've already learned that it is very hard for us and accustomed to our continuous mistakes.
    – peterh
    Commented Jan 31, 2018 at 1:38

2 Answers 2


It's "N-Deklination", and so happens for Elefant, Präsident, etc.

Although strictly speaking one can use plural, because you can say that both h and ħ (the "reduced Planck constant") are indeed Planck constants, this is not what is meant there. This is because one talks about Bestimmung; and determining one would determine the other. It's singular there.

It might have been that in the past the word Konstante was treated as a substantivized adjective, thus declined as adjective. But now it's apparently not the case.

Another Einstein example by (DWDS) is

daß andererseits die Ausbreitungsgeschwindigkeit des Lichtes im Vakuum gleich einer Konstanten c zu setzen sei [Einstein Relativitätstheorie 25]

Of course, here is (context independently now) singular.


Both forms for singular genitive are possible, der Konstante and der Konstanten. Duden marks the second variant as the predominant one in technical language (Fachsprache).

I think the reason for the existence of two forms is that Konstante is a noun derived from an adjective, konstant. Such words have that n. Since the word has taken on a meaning of its own, it has mostly lost that n. A similar case would be Gerade (a line, from gerade, straight). I think we have discussed that one here somewhere.

Anyway, there is no reason to assume that der Konstanten in the text that you cite is not singular.

  • Brief and clear answer! Commented Jan 31, 2018 at 8:04

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