The conditional marker -isi- is invariable — it never harmonises, never changes shape. All the "work" of building a conditional form is therefore in one place only: how the stem's final vowel meets that -isi-. This page walks through it verb type by type. Two constants make the whole thing easier than it looks, so learn them first.
Two things that never vary
1. The conditional uses the strong grade throughout. Unlike the present and past, where consonant gradation flips the stem to the weak grade in some persons, the conditional keeps the infinitive's own consonant in all six persons. So antaa is antaisin (not *annaisin), ottaa is ottaisin, pitää is pitäisin, lukea is lukisin (strong k, not weak *luisin). You never have to track gradation inside a conditional paradigm — pick the strong grade once and it stays.
2. The personal endings harmonise, but -isi- does not. The endings are the ordinary set — -n, -t, (nothing), -mme, -tte, -vat/-vät — and only the last one has a harmony choice (-vat back, -vät front). The -isi- itself is fixed for every verb, front or back.
| Person | saada → conditional | syödä → conditional |
|---|---|---|
| minä | saisin | söisin |
| sinä | saisit | söisit |
| hän | saisi | söisi |
| me | saisimme | söisimme |
| te | saisitte | söisitte |
| he | saisivat | söisivät |
Only the final ending differs by harmony (saisivat back, söisivät front); the -isi- is identical.
The one rule: what the stem vowel does before -isi-
Everything else reduces to how the stem's last vowel behaves when -isi- lands on it. There are exactly three cases:
| Stem ends in… | What happens | Example |
|---|---|---|
| short -a, -ä, -o, -u, -i, -y | kept (forms a diphthong with -i-) | puhu- → puhuisin; anta- → antaisin |
| -e | dropped | luke- → lukisin; tule- → tulisin |
| long vowel / diphthong | loses one vowel | saa- → saisin; syö- → söisin |
Type 1: drop the last vowel of the infinitive, add -isi-
The stem is the infinitive minus its final -a/-ä. Then apply the rule above. Stems ending in -e drop it; everything else keeps its vowel.
| Infinitive | Stem | Conditional (minä) |
|---|---|---|
| puhua (speak) | puhu- | puhuisin |
| antaa (give) | anta- | antaisin |
| ostaa (buy) | osta- | ostaisin |
| lukea (read) | luke- | lukisin |
| ymmärtää (understand) | ymmärtä- | ymmärtäisin |
Kukaan ei uskoisi, miten paljon tässä projektissa on työtä.
Nobody would believe how much work there is in this project.
Antaisitko suolan tänne päähän pöytää?
Would you pass the salt to this end of the table?
Type 2: the contraction verbs (-da/-dä)
These stems already end in a long vowel or diphthong (saa-, syö-, juo-, vie-, tuo-), so one vowel drops before -isi-. The two irregulars tehdä and nähdä behave as their hidden -ke- stems (teke-, näke-), so they simply drop the -e- like a Type 1 -e stem.
| Infinitive | Stem | Conditional (minä) |
|---|---|---|
| saada (get) | saa- | saisin |
| syödä (eat) | syö- | söisin |
| juoda (drink) | juo- | joisin |
| viedä (take/lead) | vie- | veisin |
| tehdä (do) | teke- | tekisin |
| nähdä (see) | näke- | näkisin |
Note the diphthong reductions: syö → sö, juo → jo, vie → ve — exactly as in the past tense (söin, join, vein).
Söisin nyt vaikka mitä — en ole syönyt koko päivänä.
I could eat just about anything right now — I haven't eaten all day.
Saisinko laskun, kiitos?
Could I have the bill, please?
Tekisin sen mielelläni, mutta minulla ei ole aikaa.
I'd gladly do it, but I don't have the time.
Type 3: the -e stem always drops it
Type 3 verbs (-la/-lä, -na/-nä, -ra/-rä, -sta/-stä) build their stem with a linking -e- (tulla → tule-, mennä → mene-, olla → ole-). That -e- always disappears before -isi-, so the result is beautifully uniform.
| Infinitive | Stem | Conditional (minä / hän) |
|---|---|---|
| tulla (come) | tule- | tulisin / tulisi |
| mennä (go) | mene- | menisin / menisi |
| olla (be) | ole- | olisin / olisi |
| nousta (rise) | nouse- | nousisin / nousisi |
Tulisitko meille illalla syömään?
Would you come over to ours for dinner this evening?
Olisi mukavaa, jos ehtisit paikalle jo kuudelta.
It would be nice if you could make it there by six.
Types 4–6: the vowel stems
Type 4 (-ata/-ätä) builds a stem ending in a vowel plus -a/-ä (haluta → halua-). Where that final -a is short (halua-), it is kept, giving the diphthong -ai-: haluaisin. Where the stem instead ends in a long -aa/-ää (osata → osaa-, tavata → tapaa-), one vowel drops, just like Type 2. Types 5 and 6 build -e stems (tarvita → tarvitse-, vanheta → vanhene-), so the -e drops as always.
| Infinitive | Stem | Conditional (minä) |
|---|---|---|
| haluta (want) | halua- | haluaisin |
| osata (know how) | osaa- | osaisin |
| tavata (meet) | tapaa- | tapaisin |
| tarvita (need) | tarvitse- | tarvitsisin |
| vanheta (grow old) | vanhene- | vanhenisin |
Haluaisin varata pöydän kahdelle lauantaiksi.
I'd like to book a table for two for Saturday.
Osaisitko neuvoa, miten pääsen rautatieasemalle?
Would you be able to tell me how to get to the railway station?
Common Mistakes
❌ Saadaisin kupin teetä?
Incorrect — the -da never survives; the stem is saa-, so it's saisin.
✅ Saisinko kupin teetä?
Could I have a cup of tea?
❌ Hän annaisi sinulle apua, jos pyytäisit.
Incorrect — the conditional keeps the strong grade: antaisi, not annaisi.
✅ Hän antaisi sinulle apua, jos pyytäisit.
He would give you help if you asked.
❌ Me lukeisimme enemmän, jos olisi aikaa.
Incorrect — the stem -e drops before -isi-: lukisimme.
✅ Me lukisimme enemmän, jos olisi aikaa.
We would read more if there were time.
❌ He tekivät sen mielellään, jos voisivat.
Incorrect — 'would do' is the conditional tekisivät, not the past tekivät.
✅ He tekisivät sen mielellään, jos voisivat.
They would gladly do it if they could.
Key Takeaways
- Strong grade throughout — the conditional keeps the infinitive's consonant in every person (antaisin, ottaisin, lukisin).
- -isi- is invariable; only the personal endings harmonise (söisivät front, saisivat back).
- The stem vowel before -isi-: short vowels kept (puhuisin, antaisin, haluaisin), -e dropped (lukisin, tulisin, tekisin), long vowels contract (saisin, söisin, osaisin).
- Never carry the -da/-dä infinitive into the form: saisin, not *saadaisin.
- For "would have" (olisin tehnyt), see the perfect conditional.
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Start learning Finnish→Related Topics
- The Conditional -isi-: 'would'A2 — Meet the Finnish conditional mood — the -isi- marker that packs English 'would' inside the verb (puhuisin, tulisi, olisi) for hypotheticals, wishes and politeness.
- 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.
- The Conditional for Politeness: saisinkoA2 — Finnish has no word for 'please' — politeness is the conditional: saisinko kahvia?, voisitko auttaa?, haluaisin. How to ask without sounding blunt.
- The Past Tense (imperfekti): the -i- MarkerA2 — The imperfekti slots -i- between stem and personal ending — puhuin, puhui — the plain narrative past; watch puhui (past) versus puhuu (present).