Finnish vowel harmony: why it’s talossa but metsässä
Vowel harmony is the rule that decides whether an ending uses a, o, u or ä, ö, y. Once you see the pattern, you will choose the right ending almost without thinking.
6 min read · Updated 10 October 2026
What vowel harmony is
Finnish words do not mix certain vowels. A native Finnish word has either back vowels (a, o, u) or front vowels (ä, ö, y), but not both. Endings follow the word: they come in two versions, and you pick the one that matches.
talo → talossa
house → in the house
metsä → metsässä
forest → in the forest
Puhutko suomea?
Do you speak Finnish?
Ymmärrätkö?
Do you understand?
Why? It makes words flow. Your tongue stays in the back or the front of your mouth for the whole word instead of jumping around. Try saying talossä: it feels clumsy, and to a Finn it sounds wrong straight away.
The three groups of vowels
| Group | Vowels | Example words |
|---|---|---|
| Back vowels | a, o, u | talo, kirja, Turku, ruoka |
| Front vowels | ä, ö, y | metsä, kylä, pöytä, työ |
| Neutral vowels | e, i | can appear with either group |
The neutral vowels e and i are flexible. They appear in back-vowel words (kirja, Tampere) and in front-vowel words (kieli, äiti) without changing anything.
The simple rule for endings
- Look at the vowels of the word (or of its last part, if it is a compound).
- If there is any a, o or u, use the back ending: -ssa, -sta, -lla, -ko …
- If there is no a, o or u, use the front ending: -ssä, -stä, -llä, -kö …
Notice the second step. A word with only e and i counts as a front word. That is why it is Helsingissä (in Helsinki) and tiellä (on the road), even though these words have no ä, ö or y.
Asun Helsingissä.
I live in Helsinki.
Asun Tampereella.
I live in Tampere.
Asun Turussa.
I live in Turku.
Auto on tiellä.
The car is on the road.
Quick check: scan the word for a, o or u. Found one? Back ending. None? Front ending. Tampere has an a, so it is Tampereella. Helsinki has none, so it is Helsingissä.
Endings that change with vowel harmony
Many of the most common endings come in pairs. Here are the ones you will use every day. (Some words also change their middle consonant, like katu → kadulla and pöytä → pöydällä. That is consonant gradation, a separate rule.)
| Ending | Back word | Front word |
|---|---|---|
| -ssa / -ssä (in) | talossa – in the house | metsässä – in the forest |
| -sta / -stä (from, out of) | kaupasta – from the shop | kylästä – from the village |
| -lla / -llä (on, at) | kadulla – on the street | pöydällä – on the table |
| -lta / -ltä (from, off) | asemalta – from the station | lääkäriltä – from the doctor |
| -a / -ä (partitive) | kahvia – (some) coffee | teetä – (some) tea |
| -ko / -kö (question) | Puhutko? – Do you speak? | Ymmärrätkö? – Do you understand? |
| -vat / -vät (they …) | he puhuvat – they speak | he menevät – they go |
| -nut / -nyt (has done) | olen asunut – I have lived | olen syönyt – I have eaten |
| -na / -nä (as, on a day) | lauantaina – on Saturday | ystävänä – as a friend |
Some endings never change, because they have no a, o, u, ä, ö or y in them: -n, -ksi, -lle, -ni, -si, -kin. So it is taloksi and metsäksi, talolle and metsälle.
Partitive: one of the first places you meet it
When you order or talk about amounts, you use the partitive case, and vowel harmony decides its ending:
Haluaisin kahvia ja pullaa.
I’d like some coffee and a pastry.
Saisinko vettä?
Could I have some water?
Ostin leipää ja maitoa.
I bought bread and milk.
Questions: -ko or -kö?
The question ending -ko/-kö is attached to the verb (or another word you ask about). It follows the vowels of the verb form:
| Back: -ko | Front: -kö |
|---|---|
| Onko? – Is it? / Is there? | Menetkö? – Are you going? |
| Puhutko suomea? – Do you speak Finnish? | Ymmärrätkö? – Do you understand? |
| Asutko täällä? – Do you live here? | Tiedätkö? – Do you know? |
| Haluatko kahvia? – Do you want coffee? | Pidätkö kahvista? – Do you like coffee? |
| Tuletko mukaan? – Are you coming along? | Syötkö lihaa? – Do you eat meat? |
Oletko? (Are you?) and Tuletko? use -ko because of the o and u. Menetkö? uses -kö because menet has only e.
Compound words follow the last part
Finnish builds many long words from shorter ones. In a compound, the ending follows only the last part. The first part does not matter.
| Compound | Parts | With an ending |
|---|---|---|
| kesäloma (summer holiday) | kesä + loma | kesälomalla – on summer holiday |
| työpaikka (workplace) | työ + paikka | työpaikalla – at the workplace |
| hammaslääkäri (dentist) | hammas + lääkäri | hammaslääkärissä – at the dentist |
| ruokapöytä (dining table) | ruoka + pöytä | ruokapöydällä – on the dining table |
| yliopisto (university) | yli + opisto | yliopistossa – at the university |
In a long word, find where the last word starts, then apply the rule only to that part. Kesäloma starts with front vowels, but loma is back, so: kesälomalla.
Names and loanwords
Names follow the same rule: Pekka → Pekalla, Mikko → Mikolla, Päivi → Päivillä, Ville → Villellä. Foreign names do too: Anna → Annalla, Peter → Peterillä, Lontoo → Lontoossa (in London), Berliini → Berliinissä.
Some loanwords mix both groups of vowels, such as analyysi or olympialaiset. Here usage varies, and for some words both endings are accepted. Don’t worry about these at the start; follow what you see in a dictionary.
Common mistakes
- Helsingissa → Helsingissä (only e and i, so front).
- Oletkö? → Oletko? (o is a back vowel).
- Menetko? → Menetkö? (only e, so front).
- kesälomällä → kesälomalla (the last part, loma, decides).
- teeta → teetä (only e, so front).
Vowel harmony is also a pronunciation skill. If you cannot yet hear the difference between a and ä, endings like -ssa and -ssä sound the same to you. Working on Finnish pronunciation makes vowel harmony much easier.
In speaking practice, Maija notices whether a slip is just a sound (an a that should be ä) or a real ending mistake, and explains the difference, so you learn which one to work on.
Practise with Maija
Rules stick best when you use them out loud. Maija is a Finnish speaking tutor that talks with you from Pre-A1 to C2, listens and gently corrects you. To find your level, take the free level check.
Frequently asked questions
What are the front and back vowels in Finnish?+
Back vowels are a, o and u. Front vowels are ä, ö and y. The vowels e and i are neutral and can appear with either group.
Is it -ssa or -ssä?+
Use -ssa if the word has a, o or u (talossa). Use -ssä if it has none of them (metsässä, Helsingissä). In compound words, look at the last part only.
Why is it Helsingissä and not Helsingissa?+
Helsinki has only the neutral vowels e and i. A word with no a, o or u takes front endings, so it is Helsingissä.
How do I know whether to use -ko or -kö?+
Look at the word the ending attaches to. With a, o or u it is -ko (Puhutko?). Otherwise it is -kö (Menetkö? Ymmärrätkö?).