English has one word for "but," and it does two jobs at once: it can express a plain contrast ("small but cosy") and it can correct a previous statement ("not red but blue"). German splits these two jobs between two different words. Aber handles general contrast and qualification. Sondern handles correction — and only correction, only after a negation. Because English lumps both under "but," English speakers reach for aber everywhere, which produces a sentence that is grammatically possible but means the wrong thing. The good news: there is one clean trigger to watch for, and once you train your eye to spot it, the choice becomes automatic.
The core distinction
Both aber and sondern are coordinating conjunctions, so neither changes the word order — the verb stays in second position in the clause that follows (and a comma always comes before both). The difference is purely about meaning and what licenses each one.
- aber = general "but": contrast, qualification, a surprising or limiting addition. The two halves can both be true at the same time.
- sondern = "but rather": a correction that replaces something just denied. The first clause must be negative, and the second clause supplies the right alternative. The two halves are mutually exclusive — the second cancels the first.
| aber | sondern | |
|---|---|---|
| English | but, however, yet | but rather, instead |
| First clause | can be positive or negative | must be negative |
| Relationship | contrast; both can hold | correction; second replaces first |
| Word order | V2 (coordinating) | V2 (coordinating) |
The test: is the second clause replacing the first?
Here is the practical rule. Ask two questions:
- Is the first clause negative (contains nicht, kein, nie, niemand, etc.)?
- Does the second clause replace what the first clause denied — supplying the correct version?
If the answer to both is yes, use sondern. Otherwise use aber. A negation alone is not enough; aber is perfectly fine after a negation when the second clause does not correct it but merely adds a contrasting fact.
Das ist nicht rot, sondern blau.
That's not red, but (rather) blue. (negation + correction → sondern: 'blue' replaces 'red')
Er kommt nicht heute, sondern morgen.
He's not coming today, but rather tomorrow. ('tomorrow' replaces the denied 'today')
Ich habe nicht viel Geld, aber ich bin glücklich.
I don't have much money, but I'm happy. (negation, yet NO correction — 'happy' doesn't replace 'money' → aber)
That third example is the one that proves a negation by itself does not force sondern. "I'm happy" does not correct or replace "I don't have much money"; it adds a contrasting fact. Both halves are true at once, so it is aber.
aber: contrast and qualification
Aber is the everyday workhorse. Use it whenever you want to add a contrasting, limiting, or surprising point. The two clauses sit side by side, both valid.
Die Wohnung ist klein, aber sehr gemütlich.
The flat is small, but very cosy. (both true: small AND cosy — a qualification, not a correction)
Ich würde gern mitkommen, aber ich muss noch arbeiten.
I'd love to come along, but I still have to work. (informal; contrast between wish and reality)
Das Essen war teuer, aber es hat sich gelohnt.
The meal was expensive, but it was worth it. (a limiting contrast — both facts hold)
Note that aber can also follow a negation without being a correction, as long as the second clause does not name the "right" alternative:
Ich kenne ihn nicht persönlich, aber ich habe viel über ihn gelesen.
I don't know him personally, but I've read a lot about him. (negation + added contrast → aber, not sondern)
sondern: correction after a negation
Sondern says, in effect, "no — the truth is this instead." It only works when the first clause has denied something and the second clause sets the record straight. There is no version of sondern without a preceding negation.
Wir wohnen nicht in Berlin, sondern in Potsdam.
We don't live in Berlin, but rather in Potsdam.
Das Paket ist nicht für mich, sondern für meine Nachbarin.
The parcel isn't for me, but for my neighbour. (correcting who it's for)
When the two clauses each have their own subject and verb, sondern still keeps V2 in the corrected clause:
Nicht ich habe das gesagt, sondern sie hat es behauptet.
I didn't say that — rather, she's the one who claimed it. (full corrected clause, verb 'hat' stays second)
nicht nur … sondern auch
There is one fixed correlative pattern every learner needs: nicht nur … sondern auch = "not only … but also." This is sondern's most important non-negation-correction use, because here the "negation" is the nur ("only") being denied. The second half adds rather than replaces, but German still uses sondern in this set frame.
Sie spricht nicht nur Deutsch, sondern auch Russisch und Polnisch.
She speaks not only German, but also Russian and Polish.
Das Hotel war nicht nur günstig, sondern auch direkt am Strand.
The hotel was not only cheap, but also right on the beach.
Treat nicht nur … sondern auch as a unit. The auch ("also") is essential — nicht nur … sondern without auch sounds incomplete. This correlative is covered further on the two-part conjunctions page.
Common Mistakes
Using aber where the clause corrects a negation — the single most frequent error, driven straight by English "but."
❌ Das ist nicht rot, aber blau.
Incorrect — the second clause corrects the negation, so German requires 'sondern'.
✅ Das ist nicht rot, sondern blau.
That's not red, but (rather) blue.
Using sondern when there is no negation to correct — sondern always needs a denial in front of it.
❌ Es ist klein, sondern gemütlich.
Incorrect — no negation in the first clause, so use 'aber' for the contrast.
✅ Es ist klein, aber gemütlich.
It's small, but cosy.
Dropping auch in the correlative — nicht nur … sondern auch must keep its auch.
❌ Er ist nicht nur klug, sondern fleißig.
Incorrect — the correlative needs 'auch': 'sondern auch fleißig'.
✅ Er ist nicht nur klug, sondern auch fleißig.
He's not only clever, but also hard-working.
Forgetting the comma before sondern (or aber) — both always take a preceding comma.
❌ Ich will nicht jetzt sondern später essen.
Incorrect — a comma is required before 'sondern'.
✅ Ich will nicht jetzt, sondern später essen.
I don't want to eat now, but rather later.
Key Takeaways
- English "but" splits in German: aber for general contrast, sondern for correction after a negation.
- Use sondern only when the first clause is negative and the second clause replaces what was denied ("not X, but rather Y").
- A negation alone does not force sondern — if the second clause merely adds a contrasting fact, use aber.
- nicht nur … sondern auch = "not only … but also"; keep the auch.
- Both are coordinating: word order stays V2, and both always take a comma before them.
Now practice German
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Start learning German→Related Topics
- Coordinating Conjunctions (und, aber, oder, denn, sondern)A1 — The five coordinating conjunctions — und, aber, oder, denn, sondern — link two equal main clauses without touching the word order: the verb stays in second position in both.
- aber vs sondern (but)A2 — Both translate 'but,' but sondern only follows a negation it corrects ('not X, but rather Y'); aber covers every other contrast.
- Negation: nicht and keinA1 — German's two main negators and their division of labour — kein negates nouns with an indefinite or no article, nicht negates everything else, and the choice hinges on the noun's article.
- Negation, Correction (sondern), and doch as a Positive AnswerA2 — How 'sondern' corrects a negated statement and how 'doch' contradicts a negative — German's third answer word with no English equivalent.
- Two-Part (Correlative) ConjunctionsB2 — The paired connectors — entweder...oder, weder...noch, sowohl...als auch, nicht nur...sondern auch, je...desto — and their word-order surprises, including the unique verb-final je-clause.