Open questions — the ones English builds with who, what, where, when, why — use a set of interrogative pro-words in Finnish. Unlike yes/no questions, these need no clitic -ko/-kö: the question word itself signals the question. It stands at the very front of the sentence, the verb comes next, and the subject pronoun is usually dropped.
The five core words
| Finnish | English | Note |
|---|---|---|
| kuka | who | declines (kenen, ketä, kenellä…) |
| mikä | what / which | declines (minkä, mitä, missä…) |
| missä / mistä / mihin | where at / from where / to where | three-way place split |
| milloin | when | invariable (also: koska) |
| miksi | why | invariable |
Kuka sinä olet?
Who are you?
Mitä sinä teet?
What are you doing?
Missä sinä asut?
Where do you live?
Milloin juna lähtee?
When does the train leave?
Miksi itket?
Why are you crying?
Note the order: question word → verb → (subject). You can keep sinä for clarity or emphasis, but the personal ending on the verb already tells you who, so Missä asut? is just as complete as Missä sinä asut?
kuka and mikä decline — this is the big one
The single hardest thing for English speakers is that who and what are frozen in English but fully inflected in Finnish. Which case kuka or mikä takes depends on the role it plays in the sentence — subject, possessor, object, location — exactly as any noun would.
| Case | kuka (who) | mikä (what) | Use |
|---|---|---|---|
| nominative | kuka | mikä | subject: Kuka tulee? |
| genitive | kenen | minkä | possessor: Kenen auto? |
| partitive | ketä | mitä | object: Ketä odotat? |
| inessive | kenessä | missä | in whom / where |
| illative | keneen | mihin | into whom / to where |
| adessive | kenellä | millä | who has / by what |
Kenen auto tämä on?
Whose car is this?
Ketä sinä odotat?
Who are you waiting for?
Kenellä on avaimet?
Who has the keys?
That last one is worth dwelling on. Finnish has no verb "to have"; possession is built with the adessive (see the possessive sentence). So "who has the keys?" is literally "on-whom are the keys?" — Kenellä on avaimet? The question word slots into the adessive because that is the case the sentence needs.
missä / mistä / mihin are just mikä in disguise
The place trio is not three vocabulary items to memorize separately — it is mikä in its three internal local cases:
- missä = inessive of mikä → "in what place" → where (at)
- mistä = elative of mikä → "out of what place" → from where
- mihin = illative of mikä → "into what place" → to where
The same static / from / to logic runs through the whole Finnish case system, so once you feel it here you already understand it everywhere.
Missä kirjakauppa on?
Where is the bookshop?
Mistä sinä olet kotoisin?
Where are you from?
Mihin sinä menet?
Where are you going (to)?
English collapses all three into "where", which is exactly why learners keep saying Missä menet? for "where are you going". Movement toward a goal needs mihin.
miksi is literally "into what"
A small etymological gift: miksi ("why") is nothing other than the translative of mikä — "into what, turning into what". The Finnish for "why" is built from the same word as "what", so Miksi? originally asks "to what end?" You never have to inflect it further in this meaning; it is fixed as the word for why.
Miksi sinä opiskelet suomea?
Why are you studying Finnish?
Milloin sinulla on aikaa?
When do you have time?
A few more question words
Beyond the core five you will soon meet:
- koska — "when" (a common everyday alternative to milloin): Koska juna lähtee?
- millainen — "what kind of" (it declines: millaisen, millaista): Millainen sää tänään on? ("What's the weather like today?")
- kumpi — "which of two" (genitive kumman, partitive kumpaa): Kumpi on parempi? ("Which one is better?")
For how, Finnish uses a separate pair, miten and kuinka — covered on the how questions page. For the full paradigms of every interrogative pro-word, see interrogative pronouns.
Common Mistakes
❌ Kuka sinä odotat? (leaving 'who' in the nominative as an object)
Incorrect — an object needs the partitive ketä.
✅ Ketä sinä odotat?
Who are you waiting for?
❌ Missä sinä menet? (using the static 'where' for movement)
Incorrect — going somewhere is direction, so use mihin.
✅ Mihin sinä menet?
Where are you going?
❌ Kuka auto tämä on? (using 'who' for a possessor of a thing)
Incorrect — 'whose' is the genitive kenen.
✅ Kenen auto tämä on?
Whose car is this?
❌ Mikä on tämä? (marked, English-style word order for a plain 'what is this?')
Stilted — the neutral order keeps the verb at the end: Mikä tämä on?
✅ Mikä tämä on?
What is this?
Key Takeaways
- Open question words carry the question by themselves — no -ko/-kö needed.
- Order is question word → verb → (subject), and the subject pronoun is often dropped.
- kuka and mikä decline. Pick the case the sentence needs: kenen (whose), ketä (whom), kenellä (who has).
- missä / mistä / mihin are the at / from / to cases of mikä — use mihin for movement toward a goal.
- miksi ("why") is historically the translative of mikä — you never inflect it further.
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Start learning Finnish→Related Topics
- Question Pronouns: kuka, mikä, kumpi, millainenA1 — Finnish question words for who, what/which, which-of-two, and what-kind — with their suppletive case forms kenen, minkä and kumman.
- How: miten, kuinka, millä tavallaB1 — Three ways to ask how in Finnish — miten, kuinka and millä tavalla — plus the partitive traps of kuinka paljon and kuinka monta.
- mikä vs kukaA2 — Which question word to use: kuka asks who (a person's identity), mikä asks what or which (a thing, a kind, or a name) — plus their case forms and the trap of asking *Mikä hän on?
- Alternative Questions: vaiA2 — In a genuine either/or question, Finnish 'or' is vai, never tai: Kahvia vai teetä? The vai/tai split is a top English-speaker trap.