The Weak Preterite: -aði, -di, -ði, -ti | Icelandic Grammar

To put a weak Icelandic verb into the past, you add a dental suffix — a d, ð, or t — to the stem, much as English adds -ed. The whole skill is (1) knowing which dental suffix a given verb takes, and (2) attaching the right personal endings on top. This page drills exactly that: how to pick between -aði and the short -di / -ði / -ti, and how to run the full past paradigm. We leave strong-verb vowel changes and the supine to their own pages; here it is purely the weak past tense.

Two routes to the past: -aði versus the short dental

Weak verbs split into two preterite patterns:

Class-1 -a verbs add the long suffix -aði: tala → talaði, kalla → kallaði, borða → borðaði. There is an extra -a- before the dental.
Class-2 verbs (1sg present in -i) add the short dental -di / -ði / -ti, with no linking -a-: reyna → reyndi, dæma → dæmdi, keyra → keyrði, kaupa → keypti.

How do you know which a verb is before you've memorised it? Look at the 1sg present. If "I " is the bare stem (ég tala, ég kalla), it is Class 1 → -aði. If "I " ends in -i (ég reyni, ég dæmi), it is Class 2 → short dental.

Infinitive	1sg present	Preterite	Class
tala (speak)	ég tala	talaði	1 → -aði
kalla (call)	ég kalla	kallaði	1 → -aði
reyna (try)	ég reyni	reyndi	2 → short -di
dæma (judge)	ég dæmi	dæmdi	2 → short -di

Ég talaði við hann í morgun.

I talked to him this morning. (Class 1: tala → talaði)

Hún reyndi sitt besta.

She tried her best. (Class 2: reyna → reyndi)

The full preterite paradigm: tala (Class 1)

Once you have the past stem (talað-), you add the personal endings, which are the same for every weak verb: -i / -ir / -i / -um / -uð / -u. Here is tala in full:

Person	Preterite	English
ég	talaði	I spoke
þú	talaðir	you spoke
hann/hún/það	talaði	he/she/it spoke
við	töluðum	we spoke
þið	töluðuð	you (pl.) spoke
þeir/þær/þau	töluðu	they spoke

Two things to flag. First, just as in the present, the 1sg and 3sg are identical (talaði = "I spoke" and "she spoke"); the pronoun disambiguates. Second — and this is the orthography trap — the plural forms round a→ö: töluðum, töluðuð, töluðu, all with ö. This is u-umlaut, triggered by the u in the plural endings, and it fires here because tala has an a-stem. The singular keeps the a (talaði) because its ending has no u; the plural rounds it.

💡

The plural of an -a verb's preterite rounds the stem a to ö: töluðum, kölluðum, vöknuðum. But this only happens for a-stem verbs. A verb with an o/e/i/u stem keeps its vowel: borða → borðuðum (o stays o). The -u- in the ending is the theme vowel, not a rounded a.

Við töluðum saman langt fram á nótt.

We talked together late into the night. (1pl töluðum — a→ö)

Þau borðuðu pizzu og horfðu á mynd.

They ate pizza and watched a film. (borða → borðuðu, o stays o)

Choosing the short dental: -ði, -di, or -ti

For Class-2 verbs the dental is short, and which spelling appears is decided by the sound right before it — the same assimilation that makes English "-ed" sound like /d/ in "judged" but /t/ in "watched":

-di after l, m, n: reyna → reyndi, kenna → kenndi, dæma → dæmdi. The dental hardens to -d- right after these sonorants.
-ði after a vowel or other voiced consonant (r, g): keyra → keyrði, þegja → þagði, segja → sagði. The softer ð survives here.
-ti after a voiceless consonant (p, t, k, s): kaupa → keypti, missa → missti, mæta → mætti.

The cleanest way to feel the rule is the suffix-choice trio. Say them aloud and you'll hear why each dental is what it is:

Infinitive	Stem ends in	Preterite	Why
reyna	n (voiced sonorant)	reyndi	-di after n
dæma	m (voiced)	dæmdi	-di after m
keyra	r (voiced sonorant)	keyrði	-ði after r
kaupa	p (voiceless)	keypti	-ti after p (+ vowel shift au→ey)

Hann kenndi mér að synda þegar ég var lítil.

He taught me to swim when I was little. (kenna → kenndi)

Ég keypti nýja skó í gær.

I bought new shoes yesterday. (kaupa → keypti)

Hún keyrði okkur á flugvöllinn.

She drove us to the airport. (keyra → keyrði)

A handful of Class-2 verbs, like kaupa → keypti, segja → sagði, þykja → þótti, also shift their vowel on top of taking the dental. Treat those as memorised; the dental choice still follows the sound rule.

The default for unknown verbs: -aði

Here is the strategy competitors skip. Class 1 (the -aði class) is not just large — it is open and productive. Every new verb the language acquires joins it: gúgla → gúglaði ("googled"), skanna → skannaði ("scanned"), blogga → bloggaði ("blogged"), deita → deitaði ("dated"). So if you meet a verb you don't know and have to guess its past tense, guess -aði. You will be right far more often than not, and for any loanword you will be right essentially always.

Ég gúglaði veitingastaðinn áður en við fórum.

I googled the restaurant before we went. (loanword → gúglaði)

Hún bloggaði um ferðina alla vikuna.

She blogged about the trip all week. (blogga → bloggaði)

💡

When you don't know a verb's class, default to -aði. The -a class is huge and productive — it is where loanwords and new coinages go — so "-aði unless I have specific reason to think otherwise" is a reliable fallback that keeps you talking.

Common Mistakes

❌ Ég reynaði að opna gluggann.

Incorrect — reyna is Class 2 (ég reyni), so it takes the short dental: reyndi.

✅ Ég reyndi að opna gluggann.

I tried to open the window.

Forcing -aði onto a Class-2 verb is the commonest preterite error. The -i in the present (ég reyni, ég dæmi) is your warning that the verb takes the short dental, not -aði.

❌ Ég keypdi miða á tónleikana.

Incorrect — after the voiceless p, the dental must be -t: keypti.

✅ Ég keypti miða á tónleikana.

I bought a ticket for the concert.

The dental assimilates: after a voiceless consonant it is -ti, never -di. Keypdi is impossible to pronounce the way Icelandic works; it must be keypti (and the vowel shifts to ey).

❌ Við talaðum í síma í klukkutíma.

Incorrect — the plural rounds a→ö: töluðum, not talaðum.

✅ Við töluðum í síma í klukkutíma.

We talked on the phone for an hour.

The plural endings carry u, which triggers u-umlaut on an a-stem: tala → töluðum, töluðuð, töluðu. The singular talaði keeps its a (no u in the ending), but the plural must round.

❌ Við börðuðum úti í gær.

Incorrect — borða has an o-stem, so no umlaut: borðuðum, plain o.

✅ Við borðuðum úti í gær.

We ate out yesterday.

Over-applying the umlaut is the mirror error. Borða has an o stem, not a, so nothing rounds: borðuðum. The -u- in the ending is the theme vowel, not a transformed a.

Key Takeaways

Weak verbs build the past with a dental suffix and the endings -i / -ir / -i / -um / -uð / -u.
Class 1 (-a verbs, bare 1sg present) takes -aði: tala → talaði; the plural rounds a→ö (töluðum).
Class 2 (-i present) takes the short dental, spelled -ði / -di / -ti by the sound before it: keyrði, reyndi, keypti.
A few Class-2 verbs also shift their vowel (kaupa → keypti, segja → sagði) — memorise those.
The umlaut in the plural fires only on a-stems; borða → borðuðum keeps its o.
When in doubt, guess -aði — it is the productive default and the home of every loanword.

Now practice Icelandic

Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.

Start learning Icelandic→