Plural Formation in the Partitive and Genitive | Finnish Grammar

Two plural cases carry a disproportionate share of everyday Finnish — the partitive plural ("some houses," "a lot of children," direct objects, quantities) and the genitive plural ("the houses'," "of the children," the object of most postpositions). Both are built on the -i- plural stem, and both have several endings rather than one. That is what makes them intimidating. The good news: the endings are not random — each attaches to a predictable kind of stem, and once you can see which stem you have, the ending almost picks itself. This page sorts the allomorphs out.

Partitive plural: three endings

The partitive plural ending is fundamentally a short -A (a/ä) or a long -tA (ta/tä), and which one you get depends on how the plural stem ends. In practice you meet three surface shapes:

Ending	Attaches to	Examples
-ja / -jä	plural stem ending in a diphthong -Vi (the i becomes j)	talo → taloja, kissa → kissoja, kirja → kirjoja
-ia / -iä	plural stem ending in a single -i	käsi → käsiä, poika → poikia, koira → koiria
-ita / -itä	long vowels, diphthongs, and -e / -s contracted stems	maa → maita, työ → töitä, huone → huoneita, vieras → vieraita

The first two are really the same ending: taloi- + a gives taloja because -i- between two vowels turns into j, while koiri- + a stays koiria because the -i- follows a consonant. The third, -ita/-itä, is the "heavy" ending reserved for stems that end in a long vowel (maa), a diphthong (työ), or a contracted -e/-s stem (huone, vieras).

Ostin torilta perunoita, porkkanoita ja omenoita.

I bought potatoes, carrots and apples at the market.

Meillä oli juhlissa paljon vieraita.

We had a lot of guests at the party.

Luen iltaisin lapsille satuja.

In the evenings I read fairy tales to the children.

Notice harmony doing its usual work: back-vowel words take -ja / -ia / -ita (taloja, satuja, maita), front-vowel words take -jä / -iä / -itä (kyliä, töitä, päiviä).

Suomessa on kymmeniä tuhansia järviä ja saaria.

Finland has tens of thousands of lakes and islands.

Teen töitä kotoa käsin kolmena päivänä viikossa.

I work from home three days a week.

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To choose the partitive plural ending, look at the end of the plural stem, not the dictionary form. Diphthong -Vi → -ja/-jä (taloja); single -i → -ia/-iä (koiria); long vowel or contracted stem → -ita/-itä (maita, huoneita). The -ita/-itä form is the one beginners forget exists.

Genitive plural: four endings (and lots of variation)

The genitive plural is the messiest single form in Finnish nominal morphology — several endings survive side by side, and many words accept more than one. The four you need are -jen, -ien, -iden (≈ -itten), and the old -ten.

Ending	Attaches to	Examples
-jen	diphthong -Vi stems (parallel to -ja)	talo → talojen, kissa → kissojen, kirja → kirjojen
-ien	single -i stems (parallel to -ia)	käsi → käsien, poika → poikien, koira → koirien
-iden ≈ -itten	long vowels, diphthongs, -e / -s stems	maa → maiden, työ → töiden, huone → huoneiden, vieras → vieraiden
-ten (old)	the consonant stem of certain words	lapsi → lasten, mies → miesten, nainen → naisten

The first three run exactly parallel to the partitive endings — if you know a word takes -ja in the partitive, it takes -jen in the genitive (taloja → talojen); if it takes -ita, it takes -iden (maita → maiden). That parallelism is the single most useful thing to hold onto.

Talojen hinnat ovat nousseet rajusti tänä vuonna.

House prices have risen sharply this year.

Lasten huoneet ovat yläkerrassa.

The children's rooms are upstairs.

Useiden maiden johtajat tapasivat huippukokouksessa.

The leaders of several countries met at the summit.

The old -ten genitive

A handful of very common words form their genitive plural with -ten attached to the consonant stem, not to the -i- stem: lapsi → lasten, mies → miesten, nainen → naisten, nuori → nuorten, suuri → suurten. These are not archaic — they are the ordinary, everyday forms, frozen into countless compounds:

Miestenvaatteet ovat toisessa kerroksessa, naistenvaatteet ensimmäisessä.

Men's clothes are on the second floor, women's clothes on the first.

Kirjoitin artikkelin nuorten mielenterveydestä.

I wrote an article about young people's mental health.

For most of these words a regular -ien form also exists (lapsien, miehien, naisien), but it sounds heavier and is far less common; in normal usage you should reach for lasten, miesten, naisten.

Where two endings compete

Many -iden words freely allow -itten, and the two are genuine alternatives. Maiden and maitten, huoneiden and huoneitten, vieraiden and vieraitten are all correct. The -iden form is the more neutral choice in writing and careful speech; -itten is common and fully acceptable, with a slightly more colloquial, spoken flavour. Do not agonize over the choice — pick one and be consistent.

Vieraiden takit ovat naulakossa.

The guests' coats are on the coat rack.

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The genitive plural has real, sanctioned variation — talojen also appears as taloiden, käsien as kätten, maiden as maitten. This is not you making a mistake; it is the language offering two doors. Learn one form actively and simply recognize the other when you read it.

Common Mistakes

❌ Puistossa oli paljon koirat.

Incorrect — 'a lot of dogs' is a partitive-plural quantity: koiria, not the nominative plural koirat.

✅ Puistossa oli paljon koiria.

There were a lot of dogs in the park.

❌ Ostin torilta paljon peruna.

Incorrect — potatoes as a quantity is the partitive plural perunoita (a three-syllable -a stem taking -ita), not the bare dictionary form.

✅ Ostin torilta paljon perunoita.

I bought a lot of potatoes at the market.

❌ Lapsien huoneet ovat siistit.

Incorrect in normal usage — 'the children's' is lasten, the standard -ten form; *lapsien is heavy and rare.

✅ Lasten huoneet ovat siistit.

The children's rooms are tidy.

❌ Monien maitten rajat ovat kiinni.

Not wrong, but mixed — here maiden reads better; -iden is the neutral written choice, -itten the colloquial one. Keep one register.

✅ Monien maiden rajat ovat kiinni.

Several countries' borders are closed.

❌ Talossa oli paljon huoneet.

Incorrect — 'a lot of rooms' is a partitive-plural quantity: huoneita, not the nominative plural huoneet.

✅ Talossa oli paljon huoneita.

There were a lot of rooms in the house.

Key Takeaways

Partitive plural has three shapes: -ja/-jä (taloja), -ia/-iä (koiria), -ita/-itä (maita, huoneita, vieraita).
Genitive plural runs parallel: -jen (talojen), -ien (koirien), -iden ≈ -itten (maiden, huoneiden), plus the old -ten on a consonant stem (lasten, miesten, naisten).
Learn the partitive and genitive together — a word that takes -ita also takes -iden; a word that takes -ja also takes -jen.
The -ten forms (lasten, miesten, naisten) are the normal everyday genitives, not archaisms; the regular -ien alternatives are heavier.
Several words allow two genitive plurals (maiden ~ maitten, käsien ~ kätten) — pick one, stay consistent, recognize the other.

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