Strong Verb Class Reference Key | Icelandic Grammar

Icelandic has roughly 150 strong verbs — verbs that form their past tense not by adding a dental suffix (-ði/-di/-ti, as weak verbs do) but by changing the stem vowel. This vowel change, called ablaut, is not random: it follows seven historical patterns, the seven strong-verb classes inherited unbroken from Proto-Germanic. The payoff for learning them is enormous: once you know which class a verb belongs to, its entire paradigm follows automatically — present, both preterites, the subjunctive, and the supine. This page is a reference key, not a tutorial: it lays out the seven vowel series with exemplars so you can identify any strong verb's class at a glance. For the mechanics of how each class conjugates across all persons, follow the linked class pages.

Each strong verb has four principal parts, and the four vowels in them are what define the class:

the infinitive vowel (also the present-plural and the present-singular base, before i-umlaut),
the preterite singular vowel (ég/hann in the past),
the preterite plural vowel (við/þið/þeir in the past),
the supine vowel (used after hafa: ég hef …).

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Read every strong verb as a four-vowel formula. Once you can recite, say, bíta → beit → bitum → bitið (í–ei–i–i), you don't need to memorise the conjugation table — you can generate it. The class key below gives you the formula for all seven patterns.

The seven classes at a glance

Class	Vowel series (inf. – pret. sg. – pret. pl. – supine)	Exemplars
1	í – ei – i – i	bíta, skína, líða
2	jó/jú – au – u – o	bjóða, fljúga, ljúga
3	e/i – a – u – o/u	verða, finna, drekka
4	e – a – á – o	bera, nema
5	e – a – á – e	gefa, lesa, sjá
6	a – ó – ó – a	fara, taka, standa
7	reduplicating / varied (vowel returns in supine)	halda, ganga, hlaupa

Notice two things that trip learners up. First, the supine vowel often differs from the preterite-plural vowel — Class 2 has plural u but supine o (buðum but boðið), and Class 4 has plural á but supine o (bárum but borið). Second, several classes use vowels English speakers under-pronounce — the long ó, the á, and the diphthong au are all phonemically distinct and must keep their accents.

Class 1: í – ei – i – i

The cleanest pattern. Infinitive í, preterite singular ei, preterite plural and supine i. These verbs all have a stem in í.

bíta → ég beit → við bitum → ég hef bitið

to bite → I bit → we bit → I have bitten (Class 1: í–ei–i–i)

skína → það skein → þau skinu → það hefur skinið

to shine → it shone → they shone → it has shone (Class 1)

Other Class 1 verbs: líða (pass/suffer), ríða (ride), stíga (step), grípa (grab), bíða (wait — but note beið/biðum/beðið with ð).

Class 2: jó/jú – au – u – o

Infinitive jó or jú, preterite singular au, plural u, supine o. The supine o is the giveaway — it is not the plural u.

bjóða → ég bauð → við buðum → ég hef boðið

to offer/invite → I offered → we offered → I have offered (Class 2: jó–au–u–o)

fljúga → ég flaug → við flugum → ég hef flogið

to fly → I flew → we flew → I have flown (Class 2)

Other Class 2 verbs: ljúga (lie/tell a lie), njóta (enjoy), brjóta (break), skjóta (shoot), kjósa (choose/vote).

Class 3: e/i – a – u – o/u

The largest and least tidy class. The infinitive vowel is e or i (often before a nasal or -l-/-r- cluster), preterite singular a, plural u, supine o or u. Sub-patterns depend on the following consonants.

verða → ég varð → við urðum → ég hef orðið

to become → I became → we became → I have become (Class 3: e–a–u–o)

finna → ég fann → við fundum → ég hef fundið

to find → I found → we found → I have found (Class 3: i–a–u–u)

drekka → ég drakk → við drukkum → ég hef drukkið

to drink → I drank → we drank → I have drunk (Class 3)

Other Class 3 verbs: bregða (react/flinch), binda (bind), vinna (work/win), springa (burst).

Class 4: e – a – á – o

Infinitive e, preterite singular a, plural á (long!), supine o. These are mostly verbs whose stem ends in a single sonorant (-r-, -m-).

bera → ég bar → við bárum → ég hef borið

to carry → I carried → we carried → I have carried (Class 4: e–a–á–o)

nema → ég nam → við námum → ég hef numið

to take/learn → I took → we took → I have taken (Class 4)

Other Class 4 verbs: koma (come — irregular but Class-4 vowels: kom/komum/komið), sofa (sleep), stela (steal — straddles 4).

Class 5: e – a – á – e

Just like Class 4 in the past (singular a, plural á), but the supine returns to e instead of going to o. The stem usually ends in an obstruent (-f-, -t-, -s-).

gefa → ég gaf → við gáfum → ég hef gefið

to give → I gave → we gave → I have given (Class 5: e–a–á–e)

lesa → ég las → við lásum → ég hef lesið

to read → I read → we read → I have read (Class 5)

sjá → ég sá → við sáum → ég hef séð

to see → I saw → we saw → I have seen (Class 5, irregular: contracted stem)

Other Class 5 verbs: eta/éta (eat), meta (assess), vega (weigh), biðja (ask — irregular bað/báðum/beðið).

Class 6: a – ó – ó – a

Infinitive a, preterite singular and plural both ó (long), and the supine returns to a. The doubled ó across the whole past tense makes this class easy to spot.

fara → ég fór → við fórum → ég hef farið

to go → I went → we went → I have gone (Class 6: a–ó–ó–a)

taka → ég tók → við tókum → ég hef tekið

to take → I took → we took → I have taken (Class 6, with i-umlaut in supine: tekið)

standa → ég stóð → við stóðum → ég hef staðið

to stand → I stood → we stood → I have stood (Class 6, with -nd-/-ð- alternation)

Other Class 6 verbs: aka (drive — ók/ókum/ekið), draga (pull), grafa (dig), hlæja (laugh — irregular).

Class 7: reduplicating / varied

The historical "reduplicating" class. Its defining trait in Icelandic is that the supine vowel is the same as the infinitive vowel — the verb "comes home" to its base vowel — while the preterite takes its own special vowel (often é, jó, or e). The classes are varied because the preterite vowels were originally reduplicated syllables that collapsed differently.

halda → ég hélt → við héldum → ég hef haldið

to hold/think → I held → we held → I have held (Class 7: a…é…é…a)

ganga → ég gekk → við gengum → ég hef gengið

to walk/go → I walked → we walked → I have walked (Class 7)

hlaupa → ég hljóp → við hlupum → ég hef hlaupið

to run → I ran → we ran → I have run (Class 7: au…jó…u…au)

Other Class 7 verbs: falla (fall — féll/féllum/fallið), láta (let — lét/létum/látið), gráta (cry — grét/grétum/grátið), blása (blow).

How to use this key

When you meet a new strong verb, do not memorise its conjugation cold. Instead:

Find its class by matching the infinitive vowel and stem shape against the table above.
Recall the four-vowel formula for that class.
Generate the preterite singular, preterite plural, and supine from the formula.
Check for the usual irregular fingerprints — i-umlaut in the present singular (ég fer from fara), -ð-/-d-/-t- shifts at stem boundaries, and the supine vowel that may differ from the plural.

Do this a dozen times and you stop conjugating strong verbs one by one; you conjugate patterns, and the 150 verbs collapse into seven memorable formulas plus a short list of true irregulars (vera, fá, ganga, standa).

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The supine is the part learners get wrong most, because they assume it copies the preterite-plural vowel. It often doesn't: Class 2 (buðum → boðið), Class 4 (bárum → borið), and Class 7 (héldum → haldið) all shift in the supine. Always learn the supine as the explicit fourth principal part, never derive it from the plural.

Common Mistakes

❌ Ég hef bjóðið þér.

Incorrect — the supine of bjóða is boðið (Class 2 supine vowel is o), not *bjóðið.

✅ Ég hef boðið þér.

I have invited you. — Class 2 supine: boðið.

❌ Við fárum til Akureyrar í gær.

Incorrect — the preterite plural of fara is fórum (ó), not *fárum.

✅ Við fórum til Akureyrar í gær.

We went to Akureyri yesterday. — Class 6 preterite plural: fórum.

❌ Ég hef finnað lausnina.

Incorrect — finna is strong (Class 3); its supine is fundið, not a weak *finnað.

✅ Ég hef fundið lausnina.

I have found the solution. — Class 3 supine: fundið.

❌ Hún gaf mér bók og ég hef gáfið hana áfram.

Incorrect — the supine of gefa is gefið (Class 5 supine returns to e), not *gáfið.

✅ Hún gaf mér bók og ég hef gefið hana áfram.

She gave me a book and I've passed it on. — Class 5 supine: gefið.

Key Takeaways

Strong verbs change their stem vowel (ablaut) instead of adding a dental suffix; the pattern is fixed by one of seven classes.
Every strong verb is a four-vowel formula: infinitive – preterite singular – preterite plural – supine.
The seven series: 1 í–ei–i–i, 2 jó/jú–au–u–o, 3 e/i–a–u–o, 4 e–a–á–o, 5 e–a–á–e, 6 a–ó–ó–a, 7 varied (supine returns to the infinitive vowel).
The supine vowel often differs from the preterite plural — learn it explicitly.
Know the class and you can generate the whole paradigm; ~150 strong verbs reduce to seven patterns plus a handful of true irregulars.

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