A conditional sentence links a condition (the jos-clause, "if …") to a consequence (the main clause, "then …"). Finnish has three clean patterns, and choosing between them is a matter of how real the condition is: something that may well happen, something contrary to the present, or something contrary to the past. The one thing English speakers must unlearn is the habit of putting the conditional mood in only one clause — Finnish, when the situation is unreal, puts -isi- in both the jos-clause and the main clause. Let us grade a single proposition ("if it rains, I'll stay home") through all three.
Real condition: present + present
When the condition is genuinely open — it might happen, it might not — both clauses use the present indicative. This is the everyday "if this, then that."
Jos sataa, jään kotiin.
If it rains, I'll stay home. — and it may well rain
Jos ehdit, soita minulle illalla.
If you have time, call me in the evening.
Jos näet Liisan, kerro terveisiä.
If you see Liisa, say hi from me.
Note that Finnish has no separate future tense, so jään ("I stay / I'll stay") and sataa ("it rains / it will rain") do double duty. The present carries the future meaning on its own.
Unreal present: conditional in both clauses
When the condition is contrary to fact right now — it is not raining, or is unlikely to — you shift both verbs into the conditional -isi-. This is the pattern English handles with "if it rained, I would stay," and it is exactly where transfer errors creep in: English marks only the main clause with "would," so learners write Jos sataisi, jään. In Finnish the jos-clause must be conditional too.
Jos sataisi, jäisin kotiin.
If it rained, I'd stay home. — but it isn't raining
Jos minulla olisi aikaa, matkustaisin enemmän.
If I had time, I'd travel more.
Jos olisin sinä, en ottaisi sitä työtä.
If I were you, I wouldn't take that job.
Unreal past: the perfect conditional
To talk about a condition that was contrary to fact in the past — "if it had rained, I would have stayed" — Finnish uses the perfect conditional: the conditional of olla (olisi) plus the past participle (-nut/-nyt). This is the counterfactual workhorse of the language, and it appears in both clauses.
Jos olisi satanut, olisin jäänyt kotiin.
If it had rained, I would have stayed home. — but it didn't
Jos olisin tiennyt, olisin tullut aikaisemmin.
If I had known, I would have come earlier.
Jos olisit kertonut, olisin voinut auttaa.
If you had told me, I could have helped.
The building blocks are olisin/olisit/olisi … plus a past participle: jäänyt (from jäädä), tiennyt (from tietää), tullut (from tulla), voinut (from voida). The full mechanics live on the perfect conditional page.
| Type | jos-clause | Main clause |
|---|---|---|
| Real (open) | jos sataa | jään kotiin |
| Unreal present | jos sataisi | jäisin kotiin |
| Unreal past | jos olisi satanut | olisin jäänyt kotiin |
"Unless": ellei
Finnish has a dedicated word for "unless" — ellei, a fusion of jos + ei ("if not"). It conjugates for person like any negative verb (ellen, ellet, ellei, ellemme, ellette, elleivät) and is followed by the connegative (the bare verb stem).
Ellei sada, lähdemme retkelle.
Unless it rains, we'll go on the trip.
Ellet kiirehdi, myöhästyt bussista.
Unless you hurry, you'll miss the bus.
Ellei sada is simply a tidier way of saying jos ei sada; both are correct. In the unreal patterns ellei takes the conditional just as jos does: Ellei sataisi, lähtisimme ("Were it not raining, we'd leave").
Common Mistakes
❌ Jos sataisi, jään kotiin.
Incorrect — an unreal condition needs the conditional in both clauses, so jäisin.
✅ Jos sataisi, jäisin kotiin.
If it rained, I'd stay home.
❌ Jos minulla on aikaa, matkustaisin enemmän.
Incorrect mix — the conditional main clause needs a conditional jos-clause: olisi.
✅ Jos minulla olisi aikaa, matkustaisin enemmän.
If I had time, I'd travel more.
❌ Jos olisin tietänyt, olisin tullut.
Incorrect participle — tietää forms tiennyt, not tietänyt.
✅ Jos olisin tiennyt, olisin tullut.
If I had known, I would have come.
❌ Jos ei sataa, lähdemme retkelle.
Incorrect — after ei you need the connegative sada, not sataa.
✅ Jos ei sada, lähdemme retkelle.
If it doesn't rain, we'll go on the trip.
❌ Jos olisin satanut, olisin jäänyt.
Incorrect — sataa is impersonal; the counterfactual is jos olisi satanut.
✅ Jos olisi satanut, olisin jäänyt kotiin.
If it had rained, I would have stayed home.
Key Takeaways
- Real condition: present + present — Jos sataa, jään kotiin.
- Unreal present: conditional -isi- in both clauses — Jos sataisi, jäisin kotiin.
- Unreal past: perfect conditional (olisi
- -nut/-nyt) in both — Jos olisi satanut, olisin jäänyt kotiin.
- The counterfactual workhorse is olisi
- a past participle: olisin jäänyt, olisin tiennyt.
- ellei = "unless" (jos ei), conjugated and followed by the connegative: Ellei sada ….
- More on the mood itself: conditional formation and if-sentences.
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Start learning Finnish→Related Topics
- Conditional in 'if' SentencesB1 — Choosing the mood after jos ('if'): present for real conditions, conditional in both clauses for hypotheticals, perfect conditional for past counterfactuals.
- Forming the ConditionalB1 — Build -isi- forms across all verb types: strong grade throughout, -e drops, long vowels contract (saada→saisin, tehdä→tekisin), short -a/-ä stays (antaisin).
- Condition and Concession: jos, vaikka, jottaB1 — How Finnish builds if-clauses (jos), even-though clauses (vaikka), and purpose clauses (jotta) — and why jos never means 'whether'.
- The Perfect Conditional: olisin tehnytB2 — The Finnish 'would have': olla in the conditional plus the past participle (olisin tehnyt) for counterfactual past — things that would have happened but didn't.