Stem-Changing Verbs: Spanish Grammar Made Simple

Today we’re going to take a look at one of the first concepts in Spanish grammar you’ll need to master –  stem changes. And no, unfortunately – we’re not talking about flowers. 

We’re talking about changes that some verbs undergo when you are conjugating them. 

The good news is — it’s not complicated at all! This should be a pretty simple topic that you’ll be able to understand right away. 

The bad news – it does take a bit of memorization and hard work. But then again, all languages take plenty of work, so that’s okay!

In this article, we’ll go over absolutely everything you need to learn about these changing verbs in Spanish so that you can start using them automatically like a native.  

¡A practicar! 

How to Conjugate Regular Verbs

The first thing we need to work on is reviewing conjugation. Since that is the basis of this whole concept, we’ll give it a quick review. 

Remember that normal verbs need to change when they are referring to different people. This happens in English, too! 

In English, you would say things like “I eat”, but “He eats”. 

That change is called conjugation. However in Spanish, there are many more regular conjugations, and the verbs ending in -AR, -ER, and -IR all have different changes. 

Here’s a quick review of regular verb conjugations.

So keep these normal conjugated endings in mind because you’ll need to use them, plus some irregular stem changes.

Need more help with regular verb conjugations? Check out our full guide on Spanish Regular Verb Conjugations

What is The Stem of a Verb?

So now that we’ve mentioned how to conjugate, the next step is to figure out what the stem is for these irregular verbs. Basically, the stem is the base part of the word without the ending. 

So in the verb tener, the stem is ten, and the ER is the ending. Now when we talk about stem changes, we’re referring to a vowel change in the main part of the verb. 

Now let’s take a deeper look into these changing verbs in Spanish.   

Present Tense Stem Changing Verbs 

In the present tense, stem-changing verbs are often called boot verbs because of the pattern of stem-changing that occurs. 

If you look at the stem-changing verbs conjugation tables, everything except for Nosotros and Vosotros forms has a stem change. So the verbs form the shape of a boot when looking at the chart. 

In Spanish, these stem-changing verbs are referred to as Verbos radicales. Maybe that sounds a little bit more dramatic than “boot verbs”, but it’s another way to look at it! So now, let’s go over the basic types of stem-changing verbs so we can put these “radical” changes in categories. 

E to IE

The first major type of stem change for Spanish verbs in the present tense is from E to IE. This means that the letter E in the syllable before the ending changes to the letters IE. The most common example of this stem-changing category is the word Querer (To want / To love)

So the E in the stem changes to an IE in the conjugations for Yo, Tú, Él, and Ellos. This is the most common stem-changing verb form, so it’s important to remember this one. 

In fact, many of the most common verbs in Spanish are E to IE stem-changing verbs. Here is a list of other verbs that follow this pattern as well:

• Pensar – To think
• Empezar – To start 
• Comenzar – To start
• Cerrar – To close
• Despertar – To wake up
• Negar – To deny
• Apretar – To tighten 
• Recomendar – To recommend 
• Sentarse – To sit down 
• Perder – To lose 
• Defender – To defend 
• Entender – To understand 
• Encender – To light
• Convertir – To convert 
• Mentir – To lie 
• Preferir – To prefer
• Sentir – To feel 
• Sugerir – To suggest 

And this isn’t even a complete list! As you can see, though, you can have AR, ER, and IR verbs follow this pattern, so there’s no limitation. 

You may have also noticed that many basic words are stem-changing verbs. If you think about it, this makes sense. Since the words that are the most common tend to be the most irregular, the simple words often have stem changes! 

Now let’s move on to the next type of stem-changing verbs in Spanish. 

U to UE

Jugar is actually the only verb that has this type of stem change, so you’re in luck! Once you memorize how to do the stem change for this verb, you don’t even need to apply it to anything else. This verb has its stem changed from U to UE according to this chart:

O to UE

This next stem change is actually pretty similar to the last one you just saw. The only difference here is that there are multiple verbs that follow this pattern. 

Verbs like Dormir have the infinitive stem change from the letter O to a UE like this:

This is something you’ll see quite often, and with some pretty basic vocabulary. So the earlier you learn this type of stem-changing verb conjugation, the better. To help you out, here is a list of other verbs with a UE change. 

• Morir – To die
• Poder – To be able 
• Volver – To return 
• Soler – To tend to do something
• Mover – To move
• Llover – To rain
• Doler – To hurt 
• Remover – To stir 
• Costar – To cost 
• Acordar – To remember
• Probar – To try
• Comprobar – To check 
• Renovar – To renew 
• Soñar – To dream 

Oler – To smell*

Note that on this last one, Oler is an extra-irregular verb, since it will change from O to HUE. So you get Yo huelo, tú hueles, etc.

And once again, this isn’t a comprehensive list of stem-changing verbs conjugated this way, in fact, there are many more verbs in Spanish that function like this. So keep your eye out and be wary of the letter O the syllable before the verb ending. 

E to I

This last one is not as common as some of the other stem-changing verbs in Spanish, but it still is important to watch out for them. Here, the letter E changes to a letter I in the present tense.

So in these cases, the E changes to an I. These ones can be tricky because you have to remember that it changes to an I, not an IE, like in the other category of stem-changing verbs. 

Some other examples of E to I stem-changing verbs in Spanish are:

• Medir – To measure 
• Competir – To compete 
• Impedir – To impede 
• Repetir – To repeat 
• Vestir – To dress 
• Derretir – To melt 
• Despedir – To say goodbye 
• Rendir – To give up 

The good thing is that this type of stem-changing verb has a pattern! Notice that only IR verbs follow this type of stem change. This is a key factor to notice since it will really help you with your vocabulary memorization skills. 

How to Identify Spanish Stem-Changing Verbs

Now here is the big question – how do you identify Spanish stem-changing verbs? 

Unfortunately, the short answer is: memorization. There isn’t really one key trick you can do to remember which verbs follow a regular pattern of conjugation and which ones have a stem change. 

Just like other types of irregular verbs, the only thing you can do is try and memorize them. There are some basic patterns you can pay attention to that might help you, but there’s no guarantee. 

For example, many words, like the verb Repetir, that are IR verbs and have an E will be stem-changing. Unfortunately, there’s no clear rule on how to conjugate this Spanish verb, since this fits the category for both E to I and E to IE verbs. 

The best thing you can do is to pay special attention to these stem-changing verbs in the present tense and try using memorization techniques like flashcards. 

Another great technique to learn is to challenge yourself to work on one category of verb at a time so you don’t get so overwhelmed. By learning them little by little, you’ll be better able to handle all of this memorization.

Don’t forget – the best way to learn a language is by practicing! If you want to get some first-hand experience using these stem-changing verbs in Spanish, check out how to get the most of our Spanish Conversation Classes.

Stem Changing Verbs in Other Tenses

If you have a stem-changing verb in the present tense, most likely it is also a stem-changing verb in the present subjunctive and, possibly, in the preterite tense.

For example, Querer in the present subjunctive is Yo quiera, tú quieras, etc. Then, in the preterite it’s Yo quise, tú quisiste, etc.

So if a verb is a stem-changing verb in the present indicative, the same type of change will occur in the present subjunctive.

That’s easy enough to remember the rule for these stem-changing verbs in Spanish. 

However, for the preterite, sometimes you can get the same type of stem change, but sometimes it’s just completely different. 

For example, the verb Servir is E to I in the present tense. 

• Yo sirvo, tú sirves, él sirve. (present indicative)
• Yo sirva, tú sirvas, él sirva. (present subjunctive)
• Yo serví, tú serviste, él sirvió. (preterite) 

Here you can see that the same patterns occur for the subjunctive tense, but only the third person is conjugated as a stem-changing form for the preterite. For the rest of the cases, it functions like any of the regular verbs in that tense. 

This is a common pattern for IR verbs (Preferir, Repetir, etc.), but this is by no means a firm rule. For example, Mentir is an I to IE verb in the present, but the third person preterite is also Mintió. 

The takeaway here is:

• Stem-changing verbs in the present indicative follow the same pattern for the present subjunctive.
• Stem-changing verbs in the present indicative are Red Flags for the preterite. 

All done!

Had enough irregularities yet? Stem-changing verbs in Spanish can be pretty tough for beginners at first, but like everything, La práctica hace el maestro (practice makes perfect). 

The best way to tackle these first is to first, accept them for the way there are. Sometimes languages just do weird things and you just have to go with it. And secondly, keep practicing! The more you work on it, the quicker these conjugations will become automatic in your head. And one day, you’ll wonder why you ever found it difficult in the first place. 

So if you’re ready to start putting stem-changing verbs into practice, go ahead and sign up for a free private class or a 7-day free trial of our group classes so you can show us what you got!