The main rule
Three groups of verbs change the stressed vowel of the stem: e > ie (querer: quiero), o > ue (volver: vuelvo) and e > i (pedir: pido). The change appears in yo, tú, él / ella / usted and ellos / ellas / ustedes, but never in nosotros and vosotros. Eight other verbs are irregular only in the yo form: hago, pongo, salgo, traigo, conozco, sé, doy, veo.
Stem changes: querer, volver, pedir
| Person | querer (e > ie) | volver (o > ue) | pedir (e > i) |
|---|---|---|---|
| yo | quiero | vuelvo | pido |
| tú | quieres | vuelves | pides |
| él / ella / usted | quiere | vuelve | pide |
| nosotros / nosotras | queremos | volvemos | pedimos |
| vosotros / vosotras | queréis | volvéis | pedís |
| ellos / ellas / ustedes | quieren | vuelven | piden |
The endings are the regular ones you already know (-o, -es, -e, -emos / -imos, -éis / -ís, -en). Only the vowel of the stem is different. In quieres and quieren the stress falls on the stem, so the vowel changes. In queremos and queréis the stress falls on the ending, so the stem stays as in the infinitive. If you draw a line around the four changing forms, you get the shape of a boot, which is why these are called boot verbs. The most common mistake is to put the change in nosotros too: *quieremos, *vuelvemos, *pidimos.
English verbs never change their vowel from person to person (I want, we want), so nothing in your own language warns you, and the infinitive does not show the change either. That is why you should learn each verb together with its yo form: querer, quiero. If you do not, you will say *quero and *volvo, which look logical but do not exist.
Which verbs change
| Change | Verbs | Forms |
|---|---|---|
| e > ie | querer, empezar, cerrar, preferir, entender, pensar | quiero, empiezo, cierro, prefiero, entiendo, pienso |
| o > ue | volver, dormir, poder, encontrar, contar, costar | vuelvo, duermo, puedo, encuentro, cuento, cuesta |
| e > i | pedir, servir, repetir | pido, sirvo, repito |
Jugar has the same boot with u > ue: juego, juegas, juega, jugamos, jugáis, juegan. It is the only verb that changes u.
Irregular yo forms
Eight common verbs are irregular only in the first person singular. Their other persons are completely regular (haces, hace, hacemos, hacéis, hacen).
| Infinitive | yo | tú |
|---|---|---|
| hacer | hago | haces |
| poner | pongo | pones |
| salir | salgo | sales |
| traer | traigo | traes |
| conocer | conozco | conoces |
| saber | sé | sabes |
| dar | doy | das |
| ver | veo | ves |
Watch the written accents. Sé (I know) has an accent to tell it from the small word se, which is a different word. The vosotros forms of most verbs have an accent (hacéis, salís, sabéis), but dais and veis have none, because they have only one syllable.
Examples
- ¿Qué quieres de beber? What do you want to drink?
- Vuelvo a casa a las seis. I go back home at six.
- Mi hermano duerme ocho horas. My brother sleeps eight hours.
- Nosotros pedimos una pizza. We order a pizza.
- Hago la cena y Luis pone la mesa. I make dinner and Luis sets the table.
- No puedo hablar ahora. I can't talk now.
- Marta juega al tenis los sábados. Marta plays tennis on Saturdays.
- No sé su nombre. I don't know his name.
- Vosotros veis la tele y yo salgo con Ana. You are watching TV, and I'm going out with Ana. (Spain)
Learn the verb with its yo form
Write each new verb as a pair: querer, quiero; volver, vuelvo; hacer, hago. The yo form tells you at once whether the verb has a stem change or an irregular yo, and the rest follows: change in four forms, no change in nosotros and vosotros. Querer and poder are followed directly by an infinitive: Quiero comer, puedo venir. There is no word for to between them.
Common mistakes
Nosotros quieremos un café.Nosotros queremos un café. Nosotros keeps the stem of the infinitive.Yo quero un café.Yo quiero un café. The stem vowel changes in yo: e > ie.Nosotros pidimos una pizza.Nosotros pedimos una pizza. Pedir changes only where the stem is stressed, not in nosotros.Mis padres volven a casa.Mis padres vuelven a casa. Ellos is a boot form: o > ue.Yo hazo la cena.Yo hago la cena. Hacer has the irregular yo form hago.Yo no se su nombre.Yo no sé su nombre. The verb needs the accent; se without it is a different word.Vosotros véis la tele.Vosotros veis la tele. Veis has one syllable, so it has no accent.Quiero a comer ahora.Quiero comer ahora. Querer takes the infinitive directly, with no preposition.
Questions and answers
Which Spanish verbs have stem changes in the present?
Many of the most common ones, in three patterns: e > ie (querer, pensar), o > ue (poder, volver) and e > i (pedir, servir). The infinitive does not show which pattern a verb has, so learn it with its yo form.
Why do nosotros and vosotros not change?
In these two forms the stress falls on the ending (queremos, queréis), not on the stem, and the vowel changes only when the stem is stressed. That is why the pattern is called a boot.
Does jugar change like volver?
Almost: jugar changes u > ue (juego, juegas, juega, juegan) and keeps the u in jugamos and jugáis.
Why does sé have an accent?
The accent separates the verb sé (I know) from the small word se. The other forms of saber (sabes, sabe, sabemos) have no irregularity.
Can a verb have a stem change and an irregular yo?
Yes. Tener is one: the yo form is irregular (tengo), tienes, tiene and tienen change e > ie, and tenemos and tenéis keep the stem.
Do conocer and saber mean the same?
Both are translated as to know, and here you only learn their forms: conozco, conoces and sé, sabes. The difference in use is a later topic.