What Is Vowel Harmony in Finnish Language?

Vowel harmony is a kind of agreement between vowels within a word. This harmony influences how words are built and how suffixes attach to them.

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Main Groups of Finnish Vowels

Finnish has eight vowels, divided as follows:

Back vowels	Front vowels	Neutral vowels
a, o, u	ä, ö, y	e, i

Words usually contain either back vowels or front vowels, plus any neutral vowels. The vowels in suffixes must match the harmony of the root word.

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How Does Vowel Harmony Work in Practice

If a word has back vowels, its endings use back vowels too.

talo (“a house”) → talossa (“in the house”)

If a word has front vowels, the endings also have front vowels.

hylly (“a shelf”) → hyllystä (“from a shelf”)

If a word has only neutral vowels, front vowels are used in the endings.

meri (“a sea”) → meressä (“in a sea”)

If a word has both front vowels and neutral vowels, front vowels are used in the endings.

kesä (“summer”) → kesällä (“in the summer”)

If a word has both back vowels and neutral vowels, back vowels dominate the endings.

kurssi (“a course”) → kurssissa (“in a course”)

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Vowel Harmony in Compound Words

Compound words are two or more smaller words that are joined to form one longer word, for example:

poliisi (“police”) + auto (“car”) → poliisiauto (“police car”)

Compound words can be mixed with both vowel group words. In that case the last word will dominate how the ending is formed.

jää (“ice”) + kaappi (“cabinet”) → jääkaappi (“fridge”) → jääkaapissa (“in a fridge”)

ruoka (“food”) + pöytä (“table”) → ruokapöytä (“dining table”) → ruokapöydällä (“on a dining table”)

Why Vowel Harmony Matters

For learners, vowel harmony is the key to forming words correctly. Once you grasp it, Finnish becomes more predictable and logical and you will hear how sounds naturally flow together.