Plural Formation in Finnish

Overview

Forming plurals in Finnish is more complex than simply adding an "s" as in English. Finnish has two plural markers — -t for the nominative plural and -i- for all other plural case forms. These interact with the noun's stem in various ways, including vowel changes and consonant gradation, making plural formation a topic that requires careful study at the A2 level.

The nominative plural (adding -t) is relatively straightforward and is covered as a separate concept. This article focuses on the broader plural system, particularly the -i- plural marker that appears in all non-nominative plural cases (partitive plural, genitive plural, inessive plural, etc.). Understanding this system is essential for using nouns correctly in sentences where case endings are required.

The good news is that plural patterns are systematic. Once you learn how each word type interacts with the plural -i-, you can predict the correct form for any noun.

How It Works

Nominative plural: add -t

Singular	Plural	English
talo	talot	houses
auto	autot	cars
koira	koirat	dogs
kirja	kirjat	books

Plural stem: -i- replaces or is added to the final vowel

Singular stem ends in	Change	Example (singular → plural stem)
-a	a → o + i	talo → taloi-
-ä	ä → ö + i	pöytä → pöydöi-
-a (two syllable)	a → oi	koira → koiri-
-o	o → oi	auto → autoi-
-u	u → ui	koulu → kouluj-
-i	i stays (+ context)	tuoli → tuolei-
-e	e → ei	huone → huonei-

Partitive plural

The partitive plural has several endings:

Type	Ending	Example	English
Most words	-a/-ä (on plural stem)	taloja	houses (partitive)
Some words	-ita/-itä	naisia (from nainen)	women (partitive)

Plural in other cases

Case	Singular	Plural	English
Nominative	talo	talot	houses
Genitive	talon	talojen	of houses
Partitive	taloa	taloja	houses (partitive)
Inessive	talossa	taloissa	in houses
Elative	talosta	taloista	from houses
Illative	taloon	taloihin	into houses
Adessive	talolla	taloilla	on houses

Common patterns

Word type	Nom. sg.	Nom. pl.	Gen. pl.	Part. pl.
talo-type	talo	talot	talojen	taloja
koira-type	koira	koirat	koirien	koiria
nainen-type	nainen	naiset	naisten	naisia
ihminen-type	ihminen	ihmiset	ihmisten	ihmisiä

Examples in Context

Finnish	English	Note
Talot ovat suuria.	The houses are big.	Nominative plural
Näen taloja.	I see houses.	Partitive plural
Talojen hinnat nousevat.	House prices are rising.	Genitive plural
Asun isoissa taloissa.	I live in big houses.	Inessive plural
Lapsilla on leluja.	The children have toys.	Adessive + partitive plural
Koirat juoksevat pihalla.	The dogs run in the yard.	Nominative plural
Rakastan kissoja.	I love cats.	Partitive plural
Kirjojen hinnat vaihtelevat.	Book prices vary.	Genitive plural
Ihmisten täytyy syödä.	People must eat.	Genitive plural
Lapsissa on paljon energiaa.	In children there is a lot of energy.	Inessive plural

Common Mistakes

Using singular case endings with plural nouns

• Wrong: taloissa is correct, but talossa when meaning multiple houses is wrong
• Right: Use the plural marker -i- before case endings for plural
• Why: Every case form has both singular and plural versions. The plural inserts -i- before the case ending.

Wrong vowel change in plural stem

• Wrong: koiraja (keeping -a- before plural)
• Right: koiria (-a → -i in two-syllable words)
• Why: Two-syllable words ending in -a often simply change the -a to -i for the plural stem, rather than going through -oi-.

Confusing partitive plural with partitive singular

• Wrong: Näen taloa. (singular — "I see a house (partially)")
• Right: Näen taloja. (plural — "I see houses")
• Why: Partitive plural has its own form (-ja/-jä or -ita/-itä). Make sure to use the correct number.

Practice Tips

1. Four-form sets: For each noun, practice: nominative singular, nominative plural, partitive singular, partitive plural. Example: talo, talot, taloa, taloja.
2. Plural case chains: Take one noun and decline it through all major cases in plural: talot, talojen, taloja, taloissa, taloista, taloihin, taloilla.
3. Sentence transformation: Take singular sentences and make them plural: Koira juoksee → Koirat juoksevat. Näen auton → Näen autoja.

Related Concepts

• Prerequisite: Nominative and Partitive Cases — the fundamental case system