Pretérito Perfeito: Regular -ir Verbs

Of the three verb classes, the -ir group is the most regular in the preterite. There are no spelling-change verbs to memorize, and several verbs that look tricky in the present tense turn out to be completely regular in the past. This is the easiest preterite pattern in the language.

The endings

Drop the -ir and add:

The signature forms

• -i for eu — the same short, stressed -i as the -er class: parti, abri, decidi.
• -iu for você/ele/ela — the distinctive -ir third person: partiu, abriu, decidiu. Notice the family resemblance to the -er form comeu: both end in a vowel + u, but the -ir vowel is i and the -er vowel is e.

The nós overlap, one more time

As with -ar verbs, the nós form partimos is identical to the present tense. Nós partimos is both "we leave" and "we left." Context, usually a time word, tells you which one is meant.

A table of common -ir verbs

Verbs that look irregular but aren't: dormir, sentir, preferir

Here is the genuinely useful insight for this class. Verbs like dormir (to sleep), sentir (to feel), and preferir (to prefer) change their stem vowel in the present tense — eu durmo, eu sinto, eu prefiro — which makes learners expect trouble everywhere. But in the preterite, these verbs are fully regular. The stem-vowel change is a present-tense phenomenon only; it does not reach the past.

So even though the present is eu durmo, the past is the perfectly regular eu dormi — with the original -o- of the infinitive intact.

Telling -er and -ir apart in the third person

Because the eu forms of -er and -ir verbs are both -i (comi, parti), the place where the two classes visibly diverge is the third person and the -eram/-iram plural. The -er class carries an e vowel (comeu, comeram); the -ir class carries an i vowel (partiu, partiram). This matters when you only hear the verb and have to reconstruct the infinitive: a -iu ending points you to an -ir verb, an -eu ending to an -er verb.

This contrast is worth a moment of attention because English gives you no equivalent cue — there is no family of past-tense endings in English that signals which "conjugation" a verb belongs to. In Portuguese the ending itself is information about the verb's class, and reading it fluently is part of understanding fast speech.

Why this class is the most regular

The -ir preterite has two things going for it that the others lack. First, its eu ending is -i, so — like the -er class — it never triggers a spelling change with soft consonants. Second, the stem-changing -ir verbs that complicate the present simply don't complicate the past. Put those together and you get a class where, once you know parti, partiu, partimos, partiram, you can conjugate essentially every regular -ir verb in the past without second-guessing.

A final reassurance for English speakers: unlike English, where the past tense of an -ir-type idea can be wildly unpredictable (sleep → slept, feel → felt, leave → left), the Portuguese -ir preterite is almost entirely free of surprises. The handful of truly irregular -ir verbs you will eventually meet (such as vir → vim, veio, which is actually irregular across the board) are flagged individually; the ordinary vocabulary of the class behaves itself completely.

Common Mistakes