Verb classes and model verbs

Every Spanish infinitive ends in -ar, -er, or -ir. That ending is not decoration: it sorts the verb into one of three classes, and the class determines which endings it takes in every tense. Learn one verb from each class and you can conjugate most of the language.

This page is about why that works, and where it stops working. The paradigms themselves live on the model verbs’ reference pages: hablar, correr, and sufrir.

Why there are three

Latin had four conjugation classes. Two of them sounded alike and collapsed together on the way to Spanish, leaving three. Nothing about the meaning of a verb decides its class — it is inherited, and the infinitive ending is simply the label that survived.

-ar is the one open class. When Spanish takes in a new verb it becomes an -ar verb almost without exception: googlear, tuitear, chatear. The other two classes are effectively closed. So -ar is both the largest class and the one you can guess into safely; -er and -ir you have to know.

What a model verb is for

A regular verb is a stem plus an ending. Take the infinitive, drop the last two letters, and what remains is the stem — habl-, corr-, sufr-. Everything after that is supplied by a table that depends only on the class, the tense, and the person.

That is what makes a model verb useful. The endings on hablar are not facts about hablar; they are facts about the -ar class. Learn them once and caminar, trabajar, estudiar, and several thousand others come with them.

The three classes are less different than they look

Set the three paradigms side by side and the -er and -ir classes turn out to be nearly the same class wearing different labels.

Across the presente simple, pretérito indefinido, and pretérito imperfecto — eighteen person-and-tense slots — -er and -ir verbs take identical endings in sixteen. They part company in exactly two, both in the presente simple:

Everywhere else in those tenses, if you know the -er form you know the -ir form. The pretérito indefinido and pretérito imperfecto do not distinguish them at all — corrí and sufrí, corría and sufría, take the same endings throughout.

-ar, by contrast, really is its own thing, and it is the class that stands apart in almost every tense.

The future ignores the classes entirely

The futuro simple is the odd one out, and in a useful way: it is not built on the stem at all. It is built on the whole infinitive, with one set of endings shared by all three classes.

hablar + é → hablaré · correr + é → correré · sufrir + é → sufriré

The endings are -é, -ás, -á, -emos, -éis, -án, and they are the same whatever the verb class. So the futuro simple is the one tense where the three-way split does not exist — there is nothing to choose between, and no class to remember.

One quirk worth knowing

For -ar and -ir verbs, the nosotros form is the same in the presente simple and the pretérito indefinido. Hablamos is both “we speak” and “we spoke”; sufrimos is both “we suffer” and “we suffered”. Only context tells them apart.

-er verbs are the exception: corremos is present, corrimos is past. Which means the class that is otherwise nearly identical to -ir is the one that keeps this distinction.

Where models stop helping

The catch is that the verbs you need most are the least likely to be regular.

Frequency and irregularity travel together in Spanish, as in most languages: the more a verb is used, the more it resists levelling. The result is that the handful of verbs you reach for constantly are precisely the ones no model covers — ser, estar, ir, ver, poder. Each has to be learned on its own terms.

Even andar, which looks like a plain -ar verb and behaves like one almost everywhere, breaks in the pretérito indefinido: anduve, not andé.

So the three models are not a complete system. They are a very good bet on the long tail — the thousands of ordinary verbs you will meet once each — while the short list of verbs you will meet a hundred times a day has to be memorised. That is a reasonable division of labour, and it is worth knowing which side of it a new verb falls on before assuming a pattern.