Once you can read and write the standard conjunctions, you need to be able to understand how they actually sound. In colloquial Finnish (puhekieli), the subordinators are worn down to short, unstressed pieces: kun, kuin and koska all collapse into a single ku; että becomes et; vaikka becomes vaik; and mutta becomes mut. This page is strictly descriptive — it teaches you to decode speech, chat, song lyrics and dialogue in fiction. In writing, formal speech, exams or any careful register, the full forms kun, kuin, koska, että, vaikka, mutta remain obligatory.
The great merger: ku
The most striking reduction is that three distinct standard conjunctions fall together as ku. Careful Finnish separates kun ("when / as / since"), kuin ("than") and koska ("because") — but in relaxed speech they are all just ku, and only context tells them apart.
Ku mä tulin kotiin, kaikki nukkui jo.
When I came home, everyone was already asleep. (standard: Kun tulin kotiin, kaikki nukkuivat jo.)
En tullu ku mul oli flunssa.
I didn't come because I had the flu. (standard: En tullut, koska minulla oli flunssa.)
Se on paljon isompi ku mä luulin.
It's a lot bigger than I thought. (standard: Se on paljon isompi kuin luulin.)
et — spoken että
The complementiser että ("that") shrinks to et in speech. Because et also happens to be the negative verb "you don't," listeners rely on position and intonation to keep them apart. When että is followed by a negative, the two words stay separate in speech (et… ei) where the standard language fuses them into ettei.
Mä luulen et se tulee.
I think (that) he's coming. (standard: Luulen, että hän tulee.)
Sanoin sille et mä en tuu.
I told him that I'm not coming. (standard: Sanoin hänelle, etten tule.)
A very common spoken connector is nii et ("so, and so"), the reduced niin että used to draw a consequence:
Oli jo myöhä, nii et mä lähdin kotiin.
It was already late, so I went home. (standard: Oli jo myöhä, niin että lähdin kotiin.)
vaik and mut
vaikka ("although / even if") reduces to vaik, and mutta ("but") to mut — two of the most frequent words in any Finnish conversation.
Mä meen vaik sataa.
I'll go even though it's raining. (standard: Menen, vaikka sataa.)
Halusin tulla mut mul ei ollu aikaa.
I wanted to come but I didn't have time. (standard: Halusin tulla, mutta minulla ei ollut aikaa.)
Notice how these reductions cluster with the other markers of puhekieli: mä / mul for minä / minulla, sille for hänelle, tuu for tule, ollu for ollut. The conjunctions don't reduce in isolation — they ride along with a whole spoken system covered in the puhekieli overview and dropped endings.
Register: where the line falls
The reduced forms are correct, native, and everywhere in casual life — texting, chatting, talking with friends, TV dialogue. They are simply wrong in the wrong place. An essay, a news article, a cover letter, a formal presentation or a language exam all require the full standard conjunctions. The mistake to avoid is not using ku or et in speech — that is exactly right — but letting them slip into text that calls for the careful register. Note too that in standard writing a comma precedes että, kun, koska, vaikka; transcribed speech usually drops it, which is another tell that you are looking at puhekieli. The standard conjunctions themselves are covered on koska and kun.
Common Mistakes
These "mistakes" are all register leaks — spoken reductions used where standard Finnish is required.
❌ Mielestäni tämä on tärkeä asia, ku se vaikuttaa kaikkiin.
Incorrect in writing — use koska (or kun), not spoken ku, in an essay.
✅ Mielestäni tämä on tärkeä asia, koska se vaikuttaa kaikkiin.
In my opinion this is an important matter, because it affects everyone.
❌ Toivon et voitte auttaa minua asiassa.
Incorrect in a formal email — että cannot be shortened to et in writing.
✅ Toivon, että voitte auttaa minua asiassa.
I hope that you can help me with the matter.
❌ Tuote on halvempi ku kilpailijan tuote.
Incorrect in writing — comparison 'than' is kuin, not spoken ku.
✅ Tuote on halvempi kuin kilpailijan tuote.
The product is cheaper than the competitor's product.
❌ Yritin parhaani, mut se ei riittänyt.
Incorrect in writing — write the full mutta, not spoken mut.
✅ Yritin parhaani, mutta se ei riittänyt.
I tried my best, but it wasn't enough.
Key Takeaways
- ku = spoken kun / kuin / koska merged into one; context alone disambiguates.
- et = spoken että; vaik = vaikka; mut = mutta; nii et = niin että ("so").
- These forms are correct in speech and chat, but standard kun, kuin, koska, että, vaikka, mutta are obligatory in writing and formal speech.
- Restoring the right full word from ku — was it "when," "than," or "because"? — is a comprehension skill worth practising.
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Start learning Finnish→Related Topics
- Cause and Time: koska, kun, kunnesA2 — koska gives the reason ('because'), kun marks time ('when/as'), and kunnes marks the endpoint ('until') — plus the deadly kun/kuin trap, one vowel apart.
- Spoken Finnish (puhekieli): An OverviewA2 — Everyday spoken Finnish (puhekieli) differs systematically from the written standard (yleiskieli): reduced pronouns, se/ne for people, the passive as 'we', verb contractions and a clipped conditional — a rule-governed register, not sloppy speech.
- Dropped Endings: -i, -n, -tB2 — Casual Finnish clips final sounds off words — the -i of numerals (kaksi → kaks), the -t of participles (tullut → tullu), and various worn word-final -n. Normal in speech, wrong in writing.
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