búa ("to live, to dwell") is the verb you need on day one — Hvar býrð þú? "Where do you live?" is one of the first questions anyone asks. It is also one of the most irregular verbs in the language: the present (bý), past (bjó), and past plural (bjuggum) come from three different-looking stems, so there is no smooth pattern to lean on — you simply learn the shapes. As a bonus, búa gives Icelandic two of its most useful idioms: búa til "to make/prepare" and the resultative búinn that means "finished."
Conjugation
Class: strong / irregular (an old ú-stem with a heavily reshaped past). Auxiliary: hafa — ég hef búið.
| Principal parts | |
|---|---|
| Infinitive | að búa |
| 3sg present | býr |
| 3sg past | bjó |
| Supine | búið |
| Person | Present (nútíð) | Past (þátíð) |
|---|---|---|
| ég | bý | bjó |
| þú | býrð | bjóst |
| hann / hún / það | býr | bjó |
| við | búum | bjuggum |
| þið | búið | bjugguð |
| þeir / þær / þau | búa | bjuggu |
| Person | Present subjunctive | Past subjunctive |
|---|---|---|
| ég | búi | byggi |
| þú | búir | byggir |
| hann / hún / það | búi | byggi |
| við | búum | byggjum |
| þið | búið | byggjuð |
| þeir / þær / þau | búi | byggju |
| Non-finite & imperative | |
|---|---|
| Imperative (þú) | búðu |
| Imperative (þið) | búið! |
| Supine | búið |
| Past participle (m/f/n) | búinn / búin / búið ("finished / prepared") |
| Middle voice (miðmynd) | búast (við) — "to expect"; búast til — "to get ready" |
búa í / á — "to live in / on"
To say where you live, use búa í (+ dative) for most places, and búa á (+ dative) for certain ones — notably búa á Íslandi "to live in Iceland" and street addresses (búa á Laugavegi). The dative is the case of location (where you are), as opposed to the accusative of motion into.
Ég bý í Reykjavík með kærustunni minni.
I live in Reykjavík with my girlfriend.
Hvar býrð þú núna?
Where do you live now?
Þau bjuggu á Akureyri í mörg ár.
They lived in Akureyri for many years.
búa til — "to make / prepare"
Add the particle til and búa means "to make, to prepare, to create" — used for everything from cooking to building. This is one of the highest-frequency idioms in the language.
Eigum við að búa til pizzu í kvöld?
Should we make pizza tonight?
Hún bjó til fallega köku handa mér.
She made a beautiful cake for me.
The resultative búinn — "finished"
The past participle búinn (agreeing: búinn m., búin f., búið n., búin pl.) has become a workhorse word in its own right, meaning "finished / done." Combined with að + infinitive, vera búinn að is the everyday way to say a task is complete — far more common than a plain perfect.
Ég er búinn að læra fyrir prófið.
I've finished studying for the exam. (said by a man)
Ertu búin að borða? Maturinn er að kólna.
Are you done eating? The food is getting cold. (to a woman)
Common Mistakes
❌ Ég búa í Reykjavík.
Incorrect — búa is the infinitive/plural; the 1sg present is bý
✅ Ég bý í Reykjavík.
I live in Reykjavík.
❌ Þú býr í Hafnarfirði?
Incorrect — the 2sg present keeps the -rð ending: býrð, not býr
✅ Býrð þú í Hafnarfirði?
Do you live in Hafnarfjörður?
❌ Við búðum í Þýskalandi áður.
Incorrect — the past plural is the irregular bjuggum, not a weak búðum
✅ Við bjuggum í Þýskalandi áður.
We used to live in Germany.
❌ Ég bý á Reykjavík.
Incorrect — most places take búa í; á is reserved for Ísland, regions, and street addresses
✅ Ég bý í Reykjavík.
I live in Reykjavík.
Key Takeaways
- búa / býr / bjó / búið — strong and irregular; learn the four parts as a fixed set.
- Present singular is bý / býrð / býr (note ý, and the -rð in býrð); past plural is the double-g bjuggum.
- búa í
- dative for most places; búa á
- dative for Ísland, regions, and addresses.
- dative for most places; búa á
- búa til = "to make / prepare"; vera búinn að = "to have finished."
- Auxiliary is hafa: ég hef búið.
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- í and á: 'in/on/at' and the Geography RuleA2 — The two most frequent Icelandic prepositions, both two-case — í 'in/into', á 'on/at/onto' — and the lexicalised place-name split where some towns take í and others á for no semantic reason, including the rule that 'in Iceland' is á Íslandi (because it's an island, you're 'on' it).
- vera búinn að: The Resultative 'Have Done'B1 — The everyday colloquial resultative vera búinn að + infinitive ('to have finished/already done'): ég er búinn að borða 'I've already eaten / I'm done eating'. búinn AGREES with the subject like an adjective (búinn/búin/búið), the following verb is a bare infinitive, and in speech this construction is far more common than the hafa-perfect for completed actions — over-relying on hef + supine sounds bookish.
- Strong Verb Classes 4-7B1 — The last four ablaut classes of Icelandic strong verbs: Class 4 (e–a–á–o: bera → bar, báru, borið; nema, stela), Class 5 (e–a–á–e: gefa → gaf, gáfu, gefið; lesa, sjá → sá, sáu, séð), Class 6 (a–ó–ó–a: fara → fór, fóru, farið; taka → tók, standa → stóð), and Class 7 (the reduplicating remnant with é-preterites: halda → hélt, héldu, haldið; láta → lét, falla → féll, ganga → gekk, fá → fékk) — where the most irregular-looking everyday verbs actually live.