The strong-verbs overview explained the big idea: a strong verb marks the past by changing its stem vowel (ablaut), not by adding a dental ending like the weak -aði. But the vowel doesn't change at random — strong verbs fall into seven historical classes, each with its own fixed vowel series. This page covers Classes 1-3 (Classes 4-7 are on the next page). The point of learning the classes is leverage: instead of memorising thousands of verbs one by one, you memorise a handful of vowel series and slot each verb into one. And Class 3 in particular is worth its weight in gold, because it contains some of the most common verbs in the whole language — verða "become," finna "find," vinna "work/win," drekka "drink."
The four principal parts
Every strong verb is defined by four principal parts, and from them you can build the entire conjugation. They are:
- the infinitive (gives the present stem),
- the preterite singular (ég/hann _),
- the preterite plural (þeir _),
- the supine (the -ið form used in the perfect: ég hef _).
The reason there are two past forms — singular and plural — is the single most important fact about strong verbs: the preterite singular and plural usually have different vowels. Verða is varð (sg.) but urðu (pl.); bíta is beit (sg.) but bitu (pl.). Learn each verb as a four-part chant, and the class falls out of the vowels.
Class 1: í – ei – i – i (bíta, skína, ríða)
Class 1 verbs have í in the infinitive, ei in the preterite singular, and a short i in both the preterite plural and the supine. The model verb is bíta ("to bite"). Class 1 is large and beautifully regular — once you know the series, dozens of verbs (skína "shine," ríða "ride," líða "pass/feel," stíga "step," grípa "grab," skríða "crawl") conjugate by analogy.
| Verb | Infinitive (í) | Past sg. (ei) | Past pl. (i) | Supine (i) | Meaning |
|---|---|---|---|---|---|
| bíta | bíta | beit | bitu | bitið | bite |
| skína | skína | skein | skinu | skinið | shine |
| ríða | ríða | reið | riðu | riðið | ride |
The crucial contrast is beit (sg.) vs bitu (pl.) — diphthong ei in the singular, short i in the plural — and the supine keeping the short i (bitið, never *beitið). Note the present singular keeps the infinitive's í: ég bít, hann bítur.
Hundurinn beit mig í höndina.
The dog bit me on the hand. Class 1, preterite singular 'beit' (ei).
Mýflugurnar bitu okkur alla nóttina.
The mosquitoes bit us all night. Preterite PLURAL 'bitu' (short i) — not '*beitu'.
Ég hef aldrei verið bitinn af kóngulóm.
I've never been bitten by spiders. Supine/participle 'bitinn' — short i.
Class 2: jó/jú – au – u – o (bjóða, fljúga, ljúga)
Class 2 verbs have jó or jú in the infinitive, au in the preterite singular, u in the preterite plural, and o in the supine. The model is bjóða ("to offer, invite"). Other members: fljúga "fly," ljúga "lie (tell a lie)," njóta "enjoy," brjóta "break," skjóta "shoot."
| Verb | Infinitive (jó/jú) | Past sg. (au) | Past pl. (u) | Supine (o) | Meaning |
|---|---|---|---|---|---|
| bjóða | bjóða | bauð | buðu | boðið | offer/invite |
| fljúga | fljúga | flaug | flugu | flogið | fly |
| ljúga | ljúga | laug | lugu | logið | lie (fib) |
Trace one verb across the series: bjóða → bauð → buðu → boðið. The infinitive's jó becomes the diphthong au in the singular (bauð), drops to u in the plural (buðu), and settles on o in the supine (boðið). The present singular fronts to ý by i-umlaut — ég býð, hann býður — which is a good reminder that the present vowel is a fourth vowel, separate from the three ablaut grades.
Hún bauð mér í kaffi eftir fundinn.
She invited me for coffee after the meeting. Class 2, preterite singular 'bauð' (au).
Þeir buðu okkur far heim.
They offered us a ride home. Preterite PLURAL 'buðu' (u) — not '*bauðu'.
Flugfélagið hefur boðið endurgreiðslu.
The airline has offered a refund. Supine 'boðið' (o), with 'hafa'.
Vélin flaug í gegnum þrumuveður.
The plane flew through a thunderstorm. 'fljúga' → preterite singular 'flaug' (au).
Class 3: e/i – a – u – o (verða, finna, drekka, binda)
Class 3 is the one to invest in, because it holds an outsized share of everyday verbs. The series is e or i in the present, a in the preterite singular, u in the preterite plural, and o or u in the supine. The split between singular a and plural u is the signature — varð vs urðu, fann vs fundu, drakk vs drukku.
| Verb | Infinitive | Present 1sg | Past sg. (a) | Past pl. (u) | Supine | Meaning |
|---|---|---|---|---|---|---|
| verða | verða | verð | varð | urðu | orðið | become / must |
| finna | finna | finn | fann | fundu | fundið | find / feel |
| drekka | drekka | drekk | drakk | drukku | drukkið | drink |
| vinna | vinna | vinn | vann | unnu | unnið | work / win |
| binda | binda | bind | batt | bundu | bundið | bind / tie |
Two of these are spectacularly irregular on the surface even though the vowels are regular Class 3. Verða drops its v in the supine — orðið, not *verðið — and its preterite plural switches the whole stem to urð- (urðu, not a u-umlaut of varð). Vinna likewise loses its v in the past plural and supine: unnu, unnið. The doubled consonant in finna/vinna/binda belongs to the present and infinitive (finn, vinn, bind); the past stems switch to nd or nn of a different shape (fundu, unnu, bundu). But underneath, the vowels obey a → u → o/u without fail.
Hún varð læknir eftir mörg ár í námi.
She became a doctor after many years of study. Class 3, preterite singular 'varð' (a).
Foreldrar mínir urðu áhyggjufullir.
My parents got worried. Preterite PLURAL 'urðu' (u) — the whole stem switches to urð-.
Ég fann lyklana loksins undir sófanum.
I finally found the keys under the sofa. 'finna' → preterite singular 'fann' (a).
Krakkarnir fundu egg um allan garðinn.
The kids found eggs all over the garden. Preterite plural 'fundu' (u).
Við drukkum kaffi og spjölluðum fram á nótt.
We drank coffee and chatted into the night. 'drekka' → preterite plural 'drukku' (u).
Hann hefur unnið á sama stað í þrjátíu ár.
He has worked in the same place for thirty years. 'vinna' → supine 'unnið' (the v drops).
English vs Icelandic: ablaut you already half-know
English has a fossil version of exactly this system. Ride → rode → ridden, fly → flew → flown, drink → drank → drunk, find → found — these are the Germanic strong verbs, the same ancestral classes. The difference is that English has lost most of them (regularised to -ed) and blurred the survivors, whereas Icelandic kept the full system alive and productive-looking, with the singular/plural past split that English long ago flattened. So drekka → drakk → drukku is genuinely drink → drank → drunk with the old plural drukku still distinct — a form English used to have and threw away. Recognising the cognate series (ride/ríða, bite/bíta, drink/drekka) makes the classes feel less foreign and more like a stricter version of something already in your head.
Common Mistakes
❌ Hundurinn bítaði mig.
Incorrect — 'bíta' is strong, not weak; there's no '-aði'. The past is 'beit'.
✅ Hundurinn beit mig.
The dog bit me. Class 1 preterite 'beit'.
❌ Flugurnar beitu okkur.
Incorrect — the preterite PLURAL of 'bíta' is short i: 'bitu', not '*beitu' (that keeps the singular diphthong).
✅ Flugurnar bitu okkur.
The flies bit us. Plural 'bitu'.
❌ Þeir bauðu okkur í mat.
Incorrect — the preterite plural of 'bjóða' drops to u: 'buðu', not '*bauðu'.
✅ Þeir buðu okkur í mat.
They invited us for dinner. Plural 'buðu'.
❌ Foreldrar mínir varð áhyggjufullir.
Incorrect — a plural subject needs the preterite PLURAL 'urðu', not the singular 'varð'.
✅ Foreldrar mínir urðu áhyggjufullir.
My parents got worried. Plural 'urðu'.
❌ Ég hef verðið veikur. / Ég hef vinnið hér lengi.
Incorrect — the supines drop the v: 'orðið' (from verða) and 'unnið' (from vinna), never '*verðið' or '*vinnið'.
✅ Ég hef orðið veikur. / Ég hef unnið hér lengi.
I've become ill. / I've worked here a long time. Supines 'orðið' and 'unnið'.
Key Takeaways
- A strong verb is defined by four principal parts — infinitive, preterite singular, preterite plural, supine — and the past singular and plural usually have different vowels.
- Class 1: í – ei – i – i (bíta → beit → bitu → bitið; skína, ríða, líða, stíga, grípa).
- Class 2: jó/jú – au – u – o (bjóða → bauð → buðu → boðið; fljúga, ljúga, njóta, brjóta).
- Class 3: e/i – a – u – o/u (verða → varð → urðu → orðið; finna → fann → fundu; drekka, vinna, binda) — the highest-frequency class; learn it as a block.
- Watch the surface irregularities in Class 3: verða and vinna drop the v in the supine (orðið, unnið) and switch the past-plural stem (urðu, unnu).
- These are the same ancestral series as English ride/rode/ridden and drink/drank/drunk — Icelandic just kept the whole system alive, plural split and all.
Now practice Icelandic
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Start learning Icelandic →Related Topics
- Strong Verbs and Ablaut: OverviewA2 — The strong verb system: verbs that build the past by changing their stem vowel (ablaut) instead of adding an ending, with FOUR principal parts — infinitive, preterite singular, preterite plural, supine — and the crucial split where the past singular and past plural can carry different vowels (fann vs fundu).
- 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.
- Present Tense: Strong Verbs and i-UmlautA2 — Why strong verbs change their stem vowel in the present singular but not the plural — taka → ég tek, þú tekur but við tökum, þeir taka — the i-umlaut/fronting that fronts a to e, and the crucial fact that this present vowel is separate from the preterite ablaut (tek vs tók).
- The Preterite (þátíð): UsesA2 — What the simple past tense does — the default narrative past that covers English simple past AND, often, the present perfect for completed events, with Icelandic's separate hafa + supine perfect used more selectively, and the German-style ban on the perfect with definite past-time adverbs (no *ég hef farið í gær).
- bíta (to bite)B1 — Full conjugation of the model strong Class-1 verb bíta (bít / beit / bitu / bitið), the cleanest example of the í–ei–i–i vowel series that unlocks a whole verb class (skína, ríða, líða, stíga, grípa), with its accusative object and the reciprocal middle bítast 'bite each other'.