Weak Verbs — Cheat Sheet

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Strong and weak verbs

Weak verbs form the past tense with a suffix; strong verbs change the root vowel.

Basics The two big verb groups

Group	How the past is formed	Parallels
Strong	By changing the root vowel	Eng. to give – gave, to stand – stood; Dan. at give – gav, at stå – stod
Weak	With the suffix -ð/d/t- or -að-	Eng. to mean – meant, to live – lived; Dan. at mene – mente, at leve – levede

Pattern Three series of singular endings in the present

In the present-tense plural all classes share the same endings: -um, -ið, -a (3 pl. coincides with the infinitive). The real differences are in the singular, where three series are possible:

Person	a)	b)	c)	plural (all classes)
1st	0 (zero)	-i	-a	-um
2nd	-ur	-ir	-ar	-ið
3rd	-ur	-ir	-ar	-a

a) class 1 b) classes 2 and 3 c) class 4

Summary The four classes at a glance

Class	Present sg.	i-uml.	Past	i-uml.	Participle
1 · telja, spyrja	a) -, -ur, -ur hann telur, hún spyr	always	-ð/d/t hann taldi, hún spurði	never (cancelled)	-inn; -ður/dur/tur talinn/talið, spurður/spurt
2 · heyra	b) -i, -ir, -ir hann heyrir	always	-ð/d/t hún heyrði	always	-ður/dur/tur heyrður/heyrt
3 · horfa, vaka, segja	b) -i, -ir, -ir hann horfir, hún vakir, það segir	rarely	-ð/d/t hann horfði, hún vakti, það sagði	never (cancelled)	-ður/dur/tur; -aður horfður/horft, vakaður/vakað, sagður/sagt
4 · kalla	c) -a, -ar, -ar hann kallar	irrelevant	-að (-uð) hann kallaði	irrelevant	-aður kallaður/kallað

Notes Worth remembering

Class-1 verbs whose root ends in -r, -j or a vowel take special endings, like the corresponding strong verbs: berja ‘to beat’ → ég ber, þú berð, hann ber; flýja ‘to flee’ → ég flý, þú flýrð, hún flýr.
In the past tense the vowel changes (i-umlaut is cancelled) only in class 1 (telja, spyrja) and in the class-3 verbs with -j- after the root in the infinitive (segja, þegja).
In class 1 the (masculine) participle ends in -inn or in -(ð/d/t)ur — which one has to be memorised from the dictionary. In classes 2–3 it is -(ð/d/t)ur (occasionally -aður in class 3), in class 4 — -aður.
From the modern language's point of view classes 2 and 3 are effectively one class: identical present-tense conjugation, identical past-stem formation and no root-vowel change (except the segja, þegja type).
Dictionaries mark class-2/3 verbs by the past-tense suffix and ending (-ði/di/ti) and class-4 verbs as (-aði). For class-1 verbs all principal parts are usually listed.
Historically classes 1 and 2 were a single class with -j- after the root: short-syllable verbs went to class 1, long-syllable ones to class 2, where the -j- dropped after the long root syllable, leaving the i-umlaut as its trace.
When a participle is used only in the perfect, its masculine form is not actually used — only the neuter form lives on (vakað, þagað).
Participles in -inn decline like heiðinn, in -aður — like skollitaður, in -ð/d/t + ur — like ordinary adjectives.

The four classes of weak verbs

The class is determined by the root structure; it dictates the present endings, the past suffix and the participle shape.

Class 1 telja ‘to count’, spyrja ‘to ask’

Root	Vowel with i-umlaut, an old short vowel (monophthong, no accent) + single consonant (telja, spyrja; exception leggja < legja with secondary lengthening gj > ggj)
Present	Singular of type a) -0, -ur, -ur
Past	Stem in ð/d/t, i-umlaut cancelled: telja → taldi, spyrja → spurði
Participle	Root without i-umlaut + -inn (talinn/talið) or from the past stem + -ur (spurður/spurt)

Because of the type-a singular and the -inn participles this class comes close to the strong verbs.

Class 2 heyra ‘to hear’, dæma ‘to judge’, treysta ‘to trust’

Root	Vowel with i-umlaut: an old long vowel (diphthong, accented, æ) + single consonant (heyra, drýgja, dæma), or an old short vowel + long consonant / consonant cluster (sverta, renna), or an old long vowel + consonant cluster (treysta)
Present	Singular of type b) -i, -ir, -ir
Past	Stem in ð/d/t, no vowel change: heyra → heyrði, drýgja → drýgði, dæma → dæmdi, sverta → sverti, renna → renndi, treysta → treysti
Participle	From the past stem + -ur: heyrður/heyrt, dæmdur/dæmt, svertur/svert, renndur/rennt, treystur/treyst

Class 3 vaka ‘to be awake’, horfa ‘to look’, segja ‘to say’, hafa ‘to have’

Root	Without i-umlaut (vaka, horfa, hafa), except a few verbs with j after the root that triggers i-umlaut (segja, þegja)
Present	Singular of type b) -i, -ir, -ir; exception hafa — with i-umlaut in the singular: hef, hefur, hefur
Past	Stem in ð/d/t with no vowel change (vaka → vakti, horfa → horfði, hafa → hafði) or with the i-umlaut cancelled where the present has one (sagði, þagði)
Participle	From the past stem + -ur (horfður/horft, sagður/sagt, hafður/haft) or from the root (without i-umlaut where there is one) + -að-ur (vakaður/vakað, þagaður/þagað)

Class 4 kalla ‘to call’, byrja ‘to begin’

Root	Any — the root shape is unrestricted. The most common verb type in Icelandic.
Present	Singular of type c) -a, -ar, -ar
Past	Stem in -að, the root does not change: kalla → kallaði, byrja → byrjaði
Participle	From the root + -að-ur: kallaður/kallað, byrjaður/byrjað

Present indicative

The plural is the same everywhere (-um, -ið, -a); the class only decides the singular series.

Class 1 Infinitive in -ja · series a)

The root has i-umlaut. The -j- drops in the singular.

	singular		plural
1st	ég tel, legg	1st	við teljum, leggjum
2nd	þú telur, leggur	2nd	þið teljið, leggið
3rd	hann telur, leggur	3rd	þeir telja, leggja

NB! An infinitive in -ja does not automatically place a verb in this class (byrja is class 4).

Class 2 Diphthong or old long vowel · series b)

The root has i-umlaut.

	singular		plural
1st	ég dæmi, heyri	1st	við dæmum, heyrum
2nd	þú dæmir, heyrir	2nd	þið dæmið, heyrið
3rd	hann dæmir, heyrir	3rd	þeir dæma, heyra

Class 3 vaka, horfa · series b)

The root may lack the i-umlaut.

	singular		plural
1st	ég vaki, horfi	1st	við vökum, horfum
2nd	þú vakir, horfir	2nd	þið vakið, horfið
3rd	hann vakir, horfir	3rd	þeir vaka, horfa

This class also includes hafa ‘to have’, irregular in the singular: the vowel takes i-umlaut and the endings follow series a):

	singular		plural
1st	ég hef	1st	við höfum
2nd	þú hefur	2nd	þið hafið
3rd	hann hefur	3rd	þeir hafa

Class 4 kalla, byrja · series c)

The most common verb type; the root shape is unrestricted. Note the u-umlaut in 1 pl.: kalla → köllum.

	singular		plural
1st	ég kalla, byrja	1st	við köllum, byrjum
2nd	þú kallar, byrjar	2nd	þið kallið, byrjið
3rd	hann kallar, byrjar	3rd	þeir kalla, byrja

Past indicative and past participle

Suffix -ð/d/t- (classes 1–3) or -að- (class 4) + a single set of personal endings.

Pattern Past-tense personal endings

Person	singular	plural
1st	-i	-um
2nd	-ir	-uð
3rd	-i	-u

Suffix -ð- After vowels and voiced fricatives

The root ends in a vowel, a voiced fricative (except -ð), vowel + r, -rf, -rg, sometimes -rr:

spá ‘to predict’ → spáði · hafa ‘to have’ → hafði · leggja ‘to lay’ → lagði · læra ‘to learn’ → lærði · horfa ‘to look’ → horfði · syrgja ‘to mourn’ → syrgði · þerra ‘to dry’ → þerrði

Suffix -d- After voiced stops and sonorants

The root ends in vowel + ð (with the shift ðd > dd), -dd (the suffix drops: dd+d > dd), vowel + n, -fn, -gn, -ng, -m, -mm, -lm, -rm, -mb, -lf, -fl, -lg, -gl, usually vowel + l, sometimes -rn, occasionally -ld, -nd (the suffix drops: ld+d > ld, nd+d > nd), -ll, -nn:

eyða ‘to spend’ → eyddi · brydda ‘to fit with a point’ → bryddi · reyna ‘to try’ → reyndi · nefna [nεb̥na] ‘to name’ → nefndi [nεm̥dɪ] · rigna [rɪg̊na] ‘to rain’ → rigndi [rɪηd̥ɪ] · hringja ‘to ring’ → hringdi · dæma ‘to judge’ → dæmdi · skemma ‘to damage’ → skemmdi · hylma ‘to conceal’ → hylmdi · verma ‘to warm’ → vermdi · demba ‘to dump’ → dembdi · skelfa ‘to terrify’ → skelfdi · velgja ‘to warm up’ → velgdi · sigla [sɪg̊la] ‘to sail’ → sigldi · mæla ‘to measure’ → mældi · senda ‘to send’ → sendi · fella [fεd̥la] ‘to fell’ → felldi [fεld̥ɪ] · brenna ‘to burn’ → brenndi

Suffix -t- After voiceless consonants and -ll/-nn/-ld/-nd

The root usually ends in -ll, -nn, -ld, -nd (in the last two the -d drops), in -p, -t, -k, -s, -rð (the -ð drops), rarely vowel + l, sometimes -rr, -rn:

gylla [g̊jɪd̥la] ‘to gild’ → gyllti [g̊jɪl̥tɪ] · spenna ‘to tense’ → spennti · gilda ‘to be valid’ → gilti · synda ‘to swim’ → synti · kaupa ‘to buy’ → keypti [kjʰεiftɪ] · mæta ‘to meet’ → mætti · vaka ‘to be awake’ → vakti · kyssa ‘to kiss’ → kyssti · girða ‘to fence’ → girti · mæla ‘to speak’ → mælti · sperra ‘to stretch’ → sperrti · fyrna ‘to be left over from last year’ → fyrnti [fɪn̥tɪ]

Compare the pair: mæla ‘to measure’ → mældi, but mæla ‘to speak’ → mælti. The suffix choice parallels the choice of -ðu/du/tu for þú in fused forms.

Changes The root before the suffixes -ð-, -d-, -t-

The -j- and -v- of the infinitive stem drop: selja ‘to sell’ → seldi; sökkva ‘to sink’ → sökkti.
Root-final -ð, -d, -t after a consonant drop: girða → girti; lenda ‘to land’ → lenti; svelta ‘to starve’ → svelti.
A -ð after a vowel assimilates with the suffixal -d-: veiða ‘to hunt’ → veiddi.

Class 1 Past tense and participle

The root -e- changes to -a- in the past and the participle (becoming -ö- in the past plural); exception — selja ‘to sell’ → seldi.

	singular		plural
1st	ég taldi, lagði	1st	við töldum, lögðum
2nd	þú taldir, lagðir	2nd	þið tölduð, lögðuð
3rd	hann taldi, lagði	3rd	þeir töldu, lögðu

The participle is often in -inn (declined like heiðinn), sometimes in -ð/d/t: talinn, talin, talið; lagður, lögð, lagt.

Class 2 Past tense and participle

Suffix -ð/d/t-, the root vowel does not change:

	singular		plural
1st	ég dæmdi, heyrði, steikti	1st	við dæmdum, heyrðum, steiktum
2nd	þú dæmdir, heyrðir, steiktir	2nd	þið dæmduð, heyrðuð, steiktuð
3rd	hann dæmdi, heyrði, steikti	3rd	þeir dæmdu, heyrðu, steiktu

Participles: dæmdur, dæmd, dæmt; heyrður, heyrð, heyrt; steiktur, steikt, steikt.

Class 3 Past tense and participle

Suffix -ð/d/t-, the root vowel does not change:

	singular		plural
1st	ég vakti, horfði, hafði	1st	við vöktum, horfðum, höfðum
2nd	þú vaktir, horfðir, hafðir	2nd	þið vöktuð, horfðuð, höfðuð
3rd	hann vakti, horfði, hafði	3rd	þeir vöktu, horfðu, höfðu

Participles: vakaður, vökuð, vakað (on the class-4 pattern); horfður, horfð, horft; hafður, höfð, haft.

Class 4 Past tense and participle

Suffix -að-, changing to -uð- in the plural:

	singular		plural
1st	ég kallaði, byrjaði	1st	við kölluðum, byrjuðum
2nd	þú kallaðir, byrjaðir	2nd	þið kölluðuð, byrjuðuð
3rd	hann kallaði, byrjaði	3rd	þeir kölluðu, byrjuðu

Participles: kallaður, kölluð, kallað; byrjaður, byrjuð, byrjað.