Conjunctions are the words that glue clauses together — and, but, because, if, that. Finnish sorts them into two families that behave differently, and it punctuates them by a rule that is stricter and more predictable than English. This page is the hub: it lays out the two families, gives you the one comma rule that matters, and previews the spots where a single English word splits into two Finnish ones. Each conjunction then gets its own detailed page.
The two families
Coordinating conjunctions join two equal elements — two words, two phrases, or two independent clauses — without subordinating one to the other. The main ones:
| Finnish | English |
|---|---|
| ja | and |
| sekä | and (also); both… and… |
| tai | or (in statements) |
| vai | or (in questions) |
| mutta | but |
| vaan | but rather (after a negation) |
| eli | that is, i.e., in other words |
Subordinating conjunctions head a dependent clause — one that cannot stand alone and leans on the main clause:
| Finnish | English |
|---|---|
| että | that |
| koska | because |
| kun | when, as |
| jos | if |
| vaikka | although, even though |
| jotta | so that, in order that |
| kunnes | until |
| ennen kuin | before |
A comforting fact: a subordinate clause in Finnish keeps ordinary word order. Unlike German, the verb does not jump to the end — koska haluan nähdä sinut keeps subject-verb-object just as a main clause would.
Ostan leipää ja maitoa.
I'm buying bread and milk.
Tulen, koska haluan nähdä sinut.
I'm coming because I want to see you.
The one comma rule to internalise
Finnish comma use around conjunctions is rule-governed, not stylistic. Three points cover almost everything:
- Always put a comma before a subordinate clause. Every että, koska, kun, jos, vaikka, jotta, kunnes, ennen kuin clause is fenced off with a comma: Tulen, koska haluan.
- Put a comma before mutta and vaan. These adversative coordinators take a comma: Halusin tulla, mutta en ehtinyt.
- Do not put a comma before ja, tai, or sekä when they join words or phrases: kahvia ja teetä, teetä tai kahvia.
Toivon, että tulet käymään.
I hope (that) you'll come to visit.
Halusin tulla, mutta en ehtinyt.
I wanted to come, but I didn't have time.
Where one English word splits into two
Most learner errors come from assuming English and Finnish map word-for-word. They do not. Four splits are worth previewing here; each has its own page for the details.
tai vs vai — two kinds of "or"
tai is "or" in a statement. vai is "or" in a genuine question that asks the listener to choose between the options. If a question mark and a choice are involved, it is vai.
Haluatko teetä vai kahvia?
Do you want tea or coffee?
Otan teetä tai kahvia, kumpi vain käy.
I'll have tea or coffee, whichever's fine.
More on the tai vs vai page.
mutta vs vaan — two kinds of "but"
mutta is the general "but." vaan is "but rather" — it only appears after a negation, correcting it: not X but Y.
Pidän kahvista, mutta se pitää minut hereillä.
I like coffee, but it keeps me awake.
En juo kahvia, vaan teetä.
I don't drink coffee, but (rather) tea.
More on the mutta vs vaan page.
koska vs kun — and the kun/kuin trap
koska is "because" (cause). kun is "when, as" (time) — though in speech kun also drifts into a causal "since." Keep them apart at first: reason → koska, time → kun.
Soita minulle, kun pääset perille.
Call me when you get there.
Jään kotiin, koska olen kipeä.
I'm staying home because I'm sick.
And beware the near-twin kuin, which means "than / as" in comparisons — isompi kuin ("bigger than"), not kun. One letter changes the meaning entirely. More on the koska vs kun page.
ja vs sekä
ja is the plain "and." sekä is a slightly more formal "and," and it shines in the paired frame sekä… että… ("both… and…").
Puhun sekä suomea että ruotsia.
I speak both Finnish and Swedish.
More on the ja and sekä page, and on the all-important että — the "that" that opens reported speech and thoughts.
Common Mistakes
1. Dropping the comma before a subordinate clause
❌ Tulen koska haluan nähdä sinut.
Incorrect — a comma is required before koska.
✅ Tulen, koska haluan nähdä sinut.
I'm coming because I want to see you.
Finnish fences off every subordinate clause with a comma, even where English would leave it out.
2. Using tai in a choice question
❌ Haluatko teetä tai kahvia?
Incorrect — a choice question uses vai.
✅ Haluatko teetä vai kahvia?
Do you want tea or coffee?
When you ask someone to pick between options, "or" is vai, not tai.
3. Using mutta after a negation where vaan is needed
❌ En juo kahvia, mutta teetä.
Incorrect — a not-X-but-Y correction takes vaan.
✅ En juo kahvia, vaan teetä.
I don't drink coffee, but rather tea.
After a negation that you are correcting, "but (rather)" is vaan.
4. Confusing kun ("when") with kuin ("than")
❌ Hän on pidempi kun minä.
Incorrect — comparison needs kuin.
✅ Hän on pidempi kuin minä.
He is taller than me.
Kun is temporal ("when"); kuin is comparative ("than/as"). The extra i is not optional.
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- 'and': ja, sekä … ettäA1 — Finnish 'and' is the neutral ja for ordinary joining and the correlative sekä … että for 'both … and' — plus the comma rules English speakers get wrong.
- 'or': tai vs vaiA2 — Finnish splits English 'or' in two: tai lists open options in statements, vai forces a choice in questions — get this wrong and Kahvia tai teetä? sounds off.
- 'but': mutta vs vaanA2 — Finnish has two words for 'but': mutta for general contrast and vaan for the corrective 'but rather' — and vaan is licensed only after a negation.
- 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.
- että: The 'that' ClauseA2 — että introduces complement clauses after verbs of thinking and saying (Luulen, että hän tulee), builds niin … että results, and always takes a preceding comma.