Finnish has two relative pronouns, and choosing between them is not a matter of style — it is grammar. joka is the default, used when the relative clause describes an ordinary noun. mikä takes over in a specific set of cases: when there is no noun antecedent at all (the clause refers back to a whole idea), when the antecedent is a pronoun like se or kaikki, or when it is a superlative. English collapses all of this into "which / that", so learners reach for joka everywhere and miss the places Finnish requires mikä. This page draws the line precisely.
mikä refers to a whole clause
The clearest case: sometimes what the relative clause comments on is not a single noun but the entire preceding statement. English uses a comma plus "which" for this ("He was late, which annoyed everyone"), and Finnish uses mikä, never joka:
Hän myöhästyi junasta, mikä ärsytti kaikkia.
He missed the train, which annoyed everyone.
Sää parani illaksi, mikä oli iso helpotus.
The weather improved by evening, which was a big relief.
Here mikä stands for the whole fact — "that he missed the train", "that the weather improved". You cannot use joka, because joka needs a noun to point at, and there is no noun here — only a proposition. This clause-referring mikä is one of the most useful things on this page, because English speakers instinctively want joka and it is simply wrong.
mikä after pronoun antecedents: se, kaikki, jokin
When the antecedent is a neuter or indefinite pronoun — se ("that/the thing"), kaikki ("everything/all"), jokin ("something"), mikään ("anything"), jokainen ("everyone/each") — the relative is mikä, not joka. These pronouns behave like "the thing which", and mikä is their partner.
Se, mikä on halpaa, ei ole aina hyvää.
That which is cheap isn't always good.
Kaikki, minkä näen täällä, on minulle uutta.
Everything I see here is new to me.
Kerro minulle kaikki, mitä tiedät asiasta.
Tell me everything you know about the matter.
Notice that mikä still takes its case from its own clause, exactly like joka does. In kaikki, minkä näen, the pronoun is the total object of näen, so it appears as the genitive-form object minkä; in kaikki, mitä tiedät, the verb tietää governs a partitive object, so it is mitä. The choice of mikä (versus joka) is about the antecedent; the choice of minkä versus mitä is the ordinary object-case question you already handle with nouns.
mikä after superlatives and ordinals
After a superlative (paras "best", pahin "worst", kaunein "most beautiful") and after ordinal-like limiters (ensimmäinen "first", viimeinen "last", ainoa "only"), standard Finnish uses mikä:
Tämä on paras kirja, minkä olen koskaan lukenut.
This is the best book I've ever read.
Se oli ainoa asia, mikä minua huolestutti.
That was the only thing that worried me.
Nyt on kylmintä, mitä tänä talvena on ollut.
It's now the coldest it's been this winter.
The logic is that a superlative singles out a thing by measuring it against a whole set, so the relative clause is really commenting on "the [best] one out of everything" — closer to the kaikki pattern than to a plain noun. You will hear joka here in casual speech (paras kirja, jonka olen lukenut), and it is not a catastrophe, but mikä is the form careful writers and editors expect after a superlative.
The declension: identical to interrogative mikä
Relative mikä declines exactly like the question word mikä — same mi- stem, same forms:
| Case | Form | Role in the relative clause |
|---|---|---|
| Nominative | mikä | subject ("which is …") |
| Genitive | minkä | total object ("which I …") |
| Partitive | mitä | partial object |
| Inessive | missä | "in which" |
| Elative | mistä | "from / about which" |
| Illative | mihin | "into which" |
| Adessive | millä | "with which" |
Sain juuri sen, mitä tarvitsin.
I got exactly what I needed.
The joka-vs-mikä decision, in one table
| Antecedent | Relative | Example |
|---|---|---|
| An ordinary noun | joka | mies, joka…; kirja, jonka… |
| A whole clause / idea | mikä | Hän myöhästyi, mikä ärsytti… |
| se, kaikki, jokin, mikään, jokainen | mikä | kaikki, minkä näen… |
| A superlative (paras, pahin…) | mikä | paras, minkä olen nähnyt… |
| ainoa, ensimmäinen, viimeinen | mikä | ainoa, mikä huolestuttaa… |
The default is joka; mikä is the marked, specific choice you make for the four situations in the lower rows. When in doubt about a gray case, the dedicated joka vs mikä page walks through the tricky ones.
Comparison with English
English uses "which" both for nouns ("the car, which I bought") and for whole clauses ("he left early, which upset me"), and uses "that/what" for pronoun antecedents ("everything that I own", "what I need"). Finnish splits this three ways: joka for the noun, mikä for the clause, and mikä again for the se/kaikki pronoun antecedents. The clause-referring case is where transfer errors cluster — English "which" after a comma referring to a fact must become mikä, and no amount of "it feels like a relative clause" intuition will push you to joka correctly. Anchor the rule on the antecedent, not on the English word.
Common Mistakes
❌ Hän voitti kilpailun, joka yllätti kaikki.
Incorrect — 'which' refers to the whole fact, so it must be mikä, not joka.
✅ Hän voitti kilpailun, mikä yllätti kaikki.
He won the competition, which surprised everyone.
❌ Kaikki, joka kiiltää, ei ole kultaa.
Incorrect — the antecedent kaikki takes mikä, not joka.
✅ Kaikki, mikä kiiltää, ei ole kultaa.
All that glitters is not gold.
❌ Se on paras elokuva, jonka olen nähnyt.
Nonstandard — after a superlative, careful Finnish uses mikä: minkä.
✅ Se on paras elokuva, minkä olen nähnyt.
It's the best film I've seen.
❌ Anna minulle se, joka lupasit.
Incorrect — the pronoun antecedent se takes mikä; and it's the object, so minkä.
✅ Anna minulle se, minkä lupasit.
Give me the thing you promised.
Key Takeaways
- joka is the default (ordinary noun antecedent); mikä is required for a clause antecedent, a pronoun antecedent (se, kaikki, jokin, mikään, jokainen), and after a superlative or ainoa/ensimmäinen/viimeinen.
- Clause-referring mikä ("…, which annoyed everyone") is the top transfer error — English "which" after a comma referring to a fact = mikä.
- Relative mikä declines like the interrogative: minkä, mitä, missä, mihin, millä.
- The pronoun's case still comes from its own clause (minkä = total object, mitä = partial object); the mikä-vs-joka choice is about the antecedent.
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Start learning Finnish→Related Topics
- The Relative Pronoun jokaB1 — joka links a relative clause to a specific noun — agreeing with it in number but taking the case its own clause demands (jonka, jota, jossa, jolle).
- joka vs mikä (Relative)B1 — Choosing the relative pronoun: joka points back to a specific noun antecedent, while mikä points back to a whole clause, an indefinite or superlative head, or the pronoun se.
- Relative Clauses with joka and mikäB2 — Finnish relative clauses use joka for a specific noun and mikä for a clause, a pronoun or a superlative. joka takes its case from its role inside the clause.
- 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.