Most German relative clauses use der, die, das, but three alternatives cover cases where der/die/das either sounds clumsy or is simply wrong. welcher/welche/welches is a formal, fully-declined stand-in for der/die/das, used mainly in writing to avoid an ugly der der sequence. was is the required relative after indefinite neuter antecedents (alles, nichts, etwas, das, vieles) and after a whole preceding clause. And wo(r)-compounds serve as relatives for places (die Stadt, wo …) and for prepositional relations to things (das, woran ich denke). Knowing when each one is obligatory — not just optional — is the heart of this page.
welcher: the formal substitute for der/die/das
welcher declines exactly like dieser and agrees in gender, number, and case just as der/die/das would. It is wholly interchangeable with the ordinary relative in meaning, but it belongs to a formal, written register — legal prose, academic writing, careful officialese — and sounds stilted in casual speech.
| Case | Masculine | Feminine | Neuter | Plural |
|---|---|---|---|---|
| Nominative | welcher | welche | welches | welche |
| Accusative | welchen | welche | welches | welche |
| Dative | welchem | welcher | welchem | welchen |
(There is no genitive welches in relative use — for "whose" you always fall back on dessen/deren.) The main practical motive for reaching for welcher is to break up a clash of identical-looking words, especially a der immediately after a der:
Das Buch, welches ich gerade lese, stammt aus dem Jahr 1920.
The book that I'm currently reading dates from 1920. (formal; avoids 'das, das …')
Wir suchen einen Mitarbeiter, welcher fließend Spanisch spricht.
We are seeking an employee who speaks fluent Spanish. (formal, e.g. a job advert)
was: obligatory after indefinite neuter antecedents
Here the choice is not stylistic — it is forced. After certain indefinite, neuter antecedents, you must use was, not das. The trigger words are alles (everything), nichts (nothing), etwas (something), vieles (much/many things), weniges (little), manches (some things), einiges, and the demonstrative das (that/the thing). They all share the feature of pointing at an indefinite or abstract "thing" rather than a concrete, gendered noun.
Alles, was du sagst, klingt vernünftig.
Everything (that) you say sounds reasonable.
Es gibt nichts, was mich mehr ärgert als Unpünktlichkeit.
There is nothing that annoys me more than unpunctuality.
Hast du etwas, was ich lesen könnte?
Have you got something I could read?
Das, was du gestern gesagt hast, stimmt nicht.
What you said yesterday isn't true. (das … was — 'the thing that')
The same forcing applies after a neuter superlative used as a noun: das Beste, was … ("the best thing that …"), das Schönste, was ….
Das Beste, was mir je passiert ist, war dieser Umzug.
The best thing that ever happened to me was this move.
Why was and not das? These antecedents are not real nouns with a fixed gender; they are indefinite quantifiers and abstractions. German marks that indefiniteness by switching the relative to was, the same word it uses for the abstract interrogative "what." Think of it as: definite concrete noun → der/die/das; indefinite/abstract "thing" → was.
was: referring back to a whole clause
was is also the relative you use when the antecedent is not a single word but an entire preceding clause — when "which" in English refers to the whole situation just described, not to any one noun in it.
Er kam wieder zu spät, was mich wirklich geärgert hat.
He turned up late again, which really annoyed me. (was = the whole fact that he was late)
Sie hat den Job bekommen, worüber sich die ganze Familie freut.
She got the job, which the whole family is delighted about. (clause antecedent + verb governing über → worüber)
In the second example notice that, because the verb sich freuen governs über, the clause-referring relative becomes the wo(r)-compound worüber rather than was — the same fusion you meet next.
wo(r)-compounds: relatives for places and prepositional relations to things
For a place antecedent, wo works as a relative meaning "where," often more natural than a heavier in dem / an dem:
Das ist die Stadt, wo ich aufgewachsen bin.
That's the town where I grew up.
Wir kennen ein Lokal, wo es den besten Kaffee gibt.
We know a place where they have the best coffee.
The more important pattern is the wo(r)-compound for a prepositional relation to a thing (not a person). When a verb governs a preposition and the antecedent is inanimate or abstract — including das, etwas, alles and whole clauses — German fuses the preposition with wo-, inserting an extra -r- before a vowel: an → woran, auf → worauf, über → worüber, mit → womit, von → wovon, für → wofür.
Das, woran ich gerade denke, kann ich nicht laut sagen.
What I'm thinking about right now I can't say out loud. (denken an → woran)
Es gibt nichts, worüber ich mir Sorgen machen müsste.
There's nothing I'd need to worry about. (sich Sorgen machen über → worüber)
Das Werkzeug, womit du das reparierst, liegt in der Schublade.
The tool you'll fix that with is in the drawer. (mit → womit; for things)
Crucially, wo(r)-compounds are for things. With a personal antecedent you must use preposition + relative pronoun instead (der Mann, mit dem …, never der Mann, womit). That split — womit for tools, mit dem for people — is covered in detail on relative clauses with prepositions.
Contrast with English
English uses what for headless relatives (what you said) but otherwise leans almost entirely on that / which / who, with no register-driven alternate like welcher and no obligatory switch after "everything / nothing." An English speaker freely says everything that you say, nothing that annoys me, something that I could read — always that, never what. German forbids das/die in exactly those spots and demands was. The other surprise is the wo(r)-compound: where English keeps "which" plus a stranded preposition (the thing which I'm thinking about), German fuses preposition and wo- into woran, worüber, womit. So the two errors to unlearn are using das after alles/nichts/etwas and failing to fuse the preposition into a wo- word for thing-antecedents.
Common Mistakes
❌ Alles, das du sagst, klingt vernünftig.
Incorrect — after the indefinite neuter alles, the relative must be was, not das.
✅ Alles, was du sagst, klingt vernünftig.
Everything you say sounds reasonable.
❌ Es gibt nichts, das mich mehr ärgert.
Incorrect — nichts requires was as its relative.
✅ Es gibt nichts, was mich mehr ärgert.
There's nothing that annoys me more.
❌ Er kam zu spät, das mich geärgert hat.
Incorrect — the antecedent is the whole clause, so the relative is was, not das.
✅ Er kam zu spät, was mich geärgert hat.
He came late, which annoyed me.
❌ Das, woran ich denke an, kann ich nicht sagen.
Incorrect — woran already contains an; don't strand a second an at the clause end.
✅ Das, woran ich denke, kann ich nicht sagen.
What I'm thinking about I can't say.
❌ Das Auto, was ich gekauft habe, ist rot.
Incorrect — Auto is an ordinary (neuter) noun, so use das, not was; was is for indefinite antecedents.
✅ Das Auto, das ich gekauft habe, ist rot.
The car I bought is red.
Key Takeaways
- welcher/welche/welches is a fully-declined, formal/written substitute for der/die/das, handy for avoiding a der der clash; everyday speech prefers der/die/das.
- was is obligatory (not optional) after indefinite neuter antecedents — alles, nichts, etwas, vieles, das — and after a neuter superlative noun (das Beste, was …).
- was is also the relative when the antecedent is an entire preceding clause ("…, which …").
- For places, wo works as "where"; for a prepositional relation to a thing, fuse the preposition with wo- (inserting -r- before a vowel): woran, worauf, worüber, womit.
- wo(r)-compounds are for things only — with people, use preposition + der/die/das.
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- Relative Pronouns: der, die, dasB1 — The workhorse relative pronouns der/die/das take their gender and number from the noun outside the clause but their case from their role inside it — and the clause is verb-final.
- Relative Clauses with PrepositionsB2 — German never strands a preposition: it pied-pipes to the front of the relative clause, sets the case of the pronoun, and for thing-antecedents fuses into a wo-compound.
- jemand, niemand, etwas, nichts, allesA2 — The core German indefinite pronouns — including the etwas Gutes pattern that turns an adjective into a capitalized noun.