welcher vs was für ein in Questions

German has two ways to ask a "which / what kind" question, and English speakers constantly pick the wrong one because English blurs the line. Welcher asks you to select from a known set ("which one of these?"); was für einer asks you to describe the type or character of something ("what kind of one?"). This page deals with both as pronouns — that is, standing on their own, with no noun behind them. (When they sit in front of a noun as determiners, the logic is the same but the endings differ slightly; see the cross-references below.)

welcher: picking one out of a known set

Welcher means "which one." You use it when there is a limited, identifiable set of things in the room, on the table, in the conversation — and you want the listener to point to one of them. The choice is constrained: the answer is already among the options both speakers can see or have in mind.

As a standalone pronoun, welcher takes the strong der-word endings, so it visibly agrees with the gender, number, and case of the noun it replaces:

The ending tells the listener exactly what category of thing you mean even when the noun itself is omitted, because it was just mentioned.

In the first sentence welcher is masculine nominative (it replaces der Mantel); in the second, welchen is masculine accusative (the object of möchtest); in the third, welchem is neuter dative (after in). The ending does the work that English signals with the bare phrase "which one."

was für einer: asking about the type or character

Was für means "what kind of," and as a standalone pronoun it becomes was für einer / eine / eins. You use it when you want a description — the type, quality, or character of something — and crucially when there is no fixed set to choose from. The answer is open-ended: "a red one," "an expensive one," "the boring kind."

The einer part is the indefinite pronoun and takes the strong endings (einer masculine, eine feminine, eins neuter); the für is not governing a case here — this is a fixed idiom, and the case of einer reflects the role of the whole phrase in the sentence, not the preposition für.

Notice the answers these questions invite: not "the second one" but "a mountain bike," "a golden retriever," "an acoustic one." That open, descriptive answer is the signature of was für.

The real difference: presupposition

Here is the insight that makes the choice automatic. It is not a vocabulary difference — it is a difference in what the question assumes.

• Welcher presupposes a known, limited set. Asking "Welcher?" only makes sense if both speakers already have the candidates in mind. You are narrowing down.
• Was für einer presupposes no set at all. You are asking the listener to characterize something out of the whole universe of possibilities. You are opening up.

Compare these two replies to the same statement:

Both are grammatical and both are common — but they ask for genuinely different answers. Welches? expects you to identify a particular member of a set ("the blue Golf we saw last week"). Was für eins? expects a description ("a little electric city car"). A native speaker hears the difference instantly.

This is exactly the line English smears together. English "which?" leans toward selection and English "what?" / "what kind?" leans toward description, but everyday English happily says "What car did you buy?" when it means "which one." German forces you to decide whether you are selecting or describing, and to mark that decision in the question word.

Why English speakers struggle

English has no separate pronoun for "what kind of one." We pad it out into a phrase — "what kind," "what sort," "what type" — and we often skip it entirely, leaning on "which" to do double duty. Because welcher is the first of the two that learners meet, they tend to overuse it and reach for welcher even when they mean "what sort of thing is it?" The result sounds odd to Germans: as if you were asking them to pick from a list that was never offered.

Common Mistakes

Key Takeaways

• welcher / welche / welches = "which one," for selecting from a known, limited set. It takes strong der-word endings and agrees in gender, number, and case.
• was für einer / eine / eins = "what kind of one," for asking about type or character when there is no fixed set. The einer carries the strong endings.
• The choice is about presupposition: welcher assumes shared candidates ("which of these?"); was für assumes none ("what sort altogether?").
• English merges these into "which / what," so when in doubt, ask yourself: am I narrowing down a known list (welcher) or asking for a description (was für einer)?