Finnish Vowel Harmony Explained: A Simple Guide for Beginners

Finnish has eight vowels:

a, e, i, o, u, y, ä, ö

For vowel harmony, we can divide these vowels into three groups.

Finnish Vowel Harmony Explained: A Simple Guide for Beginners

What Is Vowel Harmony in Finnish?

If you have started learning Finnish, you may have noticed that many Finnish endings have two different forms.

For example:

• -ssa / -ssä → talossa, metsässä

• -sta / -stä → talosta, metsästä

• -lla / -llä → autolla, pöydällä

• -ko / -kö → Onko? Syötkö?

But how do you know which ending to choose?

The answer is Finnish vowel harmony, or vokaaliharmonia in Finnish. Vowel harmony is one of the basic rules of Finnish grammar, and understanding it will make learning Finnish cases and verb forms much easier. In this guide, I’ll explain Finnish vowel harmony step by step with simple examples.

Back Vowels: A, O, U

The Finnish back vowels are:

a, o, u

For example:

• talo – house

• auto – car

• koulu – school

Words containing a, o, or u take the back-vowel form of the ending.

For example:

talo → talossa

auto → autossa

koulu → koulussa

Front Vowels: Ä, Ö, Y

The Finnish front vowels are:

ä, ö, y

For example:

• metsä – forest

• pöytä – table

• kylä – village

• yö – night

These words take endings containing ä.

For example:

metsä → metsässä

pöytä → pöydällä

kylä → kylässä

Neutral Vowels: E and I

The vowels e and i are neutral. They can appear together with either back or front vowels.

For example:

koira → koirassa

Although koira contains i, it also contains the back vowels o and a, so we use -ssa. In other words, e and i do not determine the ending when a word also contains back or front vowels.

What If a Word Contains Only E and I?

What happens when there are no back vowels or front vowels at all?

If a word contains only the neutral vowels e and i, it takes the front-vowel form of the ending.

For example:

kieli → kielessä

meri → meressä

tie → tiellä

So if you see only e and i, choose the front-vowel form.

The Basic Finnish Vowel Harmony Rule

The basic rule is simple:

If the word has A, O, or U → use A or O in the ending.

If the word does not have A, O, or U → use Ä or Ö in the ending.

For example:

talo → talossa

The word talo has a and o, so we use -ssa.

koulu → koulussa

The word koulu has o and u, so we use -ssa.

metsä → metsässä

The word metsä does not have a, o, or u, so we use -ssä.

kieli → kielessä

The word kieli does not have a, o, or u, so we use -ssä.

The same rule works with other endings:

-ssa / -ssä

-sta / -stä

-lla / -llä

-ko / -kö

So, when you are not sure which form to use, simply check:

Does the word have A, O, or U?

Yes → A / O

No → Ä / Ö

What If There Are Both Front and Back Vowels?

So far, we have seen that when a word has back vowels (a, o, u), we use A or O in the ending, and when it has front vowels (ä, ö, y), we use Ä or Ö.

But what happens if a word contains both back and front vowels? This often happens in compound words, which are words made by combining two or more words.

For example:

kirjahylly = kirja (book) + hylly (shelf)

The first part, kirja, has the back vowel a, while the second part, hylly, has the front vowel y. In compound words, the ending follows the vowel harmony of the last part of the word.

kirjahylly → kirjahyllyssä

Because the last part, hylly, has front vowels, we use -ssä.

Another example:

jäätelökauppa = jäätelö (ice cream) + kauppa (shop)

Jäätelö has front vowels ä and ö, while kauppa has back vowels a and u. Because the last part, kauppa, has back vowels, we use -ssa:

jäätelökauppa → jäätelökaupassa

So, for compound words, remember to look at the last part of the word.

Why Is Finnish Vowel Harmony Important?

Vowel harmony may seem like a small pronunciation or spelling rule at first, but it appears throughout Finnish grammar.

You will encounter it when learning:

• Finnish grammatical cases

• location endings

• question forms

• some verb forms

• many other suffixes

This means that learning vowel harmony now will make many later Finnish grammar topics easier. Instead of memorizing every form as a separate word, you can understand why the ending changes. That is one of the advantages of learning the patterns behind Finnish grammar.

Watch My Video on Finnish Vowel Harmony

Want to see Finnish vowel harmony explained with examples?

In this video lesson, I explain how vowel harmony works and how to choose between endings with A/O and Ä/Ö. You can also hear the Finnish words pronounced, which can make the pattern easier to understand and remember.

Want to Practice Finnish With Me?

Knowing the grammar rule is an important first step, but the next step is learning how to use Finnish in real situations.

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In my lessons, we can combine these areas and build a learning plan based on what works for you.

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