Stem-Changing Verbs: o to ue in Spanish

Overview

The o → ue stem change is the second major stem-changing pattern in Spanish, and at the A1 level it includes many high-frequency verbs like dormir (to sleep), volver (to return), encontrar (to find), and poder (to be able to). Just like the e → ie pattern, the change occurs in stressed syllables and follows the same "boot pattern" across the conjugation.

Once you understand how the e → ie pattern works, the o → ue pattern is easy to learn because it follows exactly the same logic. The o in the stem becomes ue in all forms except nosotros and vosotros. Recognizing this pattern means you can confidently conjugate a large group of common verbs.

How It Works

The boot pattern

Subject	Change?	dormir (to sleep)	volver (to return)	encontrar (to find)
yo	Yes	duermo	vuelvo	encuentro
tú	Yes	duermes	vuelves	encuentras
él/ella/usted	Yes	duerme	vuelve	encuentra
nosotros/as	No	dormimos	volvemos	encontramos
vosotros/as	No	dormís	volvéis	encontráis
ellos/ellas/ustedes	Yes	duermen	vuelven	encuentran

Common o → ue verbs

Verb	Class	Meaning
dormir	-ir	to sleep
volver	-er	to return, to come back
encontrar	-ar	to find
recordar	-ar	to remember
contar	-ar	to count / to tell
poder	-er	to be able to, can
costar	-ar	to cost
morir	-ir	to die
almorzar	-ar	to have lunch
soñar	-ar	to dream
mostrar	-ar	to show
probar	-ar	to try / to taste
devolver	-er	to return (something)

Jugar: the unique u → ue verb

The verb jugar (to play) is the only verb in Spanish with a u → ue stem change: juego, juegas, juega, jugamos, jugáis, juegan. It follows the same boot pattern but starts from u instead of o.

Examples in Context

Spanish	English	Note
Duermo ocho horas.	I sleep eight hours.	o → ue in yo form
¿Cuándo vuelves?	When do you come back?	Common question
No encuentro las llaves.	I can't find the keys.	Everyday frustration
¿Recuerdas su nombre?	Do you remember their name?	Memory
¿Cuánto cuesta?	How much does it cost?	Shopping essential
Almorzamos a las dos.	We have lunch at two.	No change in nosotros
Los niños juegan en el parque.	The children play in the park.	jugar: u → ue
Puedo ayudarte.	I can help you.	poder: o → ue
Cuento hasta diez.	I count to ten.	contar: o → ue
Vuelven mañana.	They come back tomorrow.	3rd person plural

Common Mistakes

Applying the stem change to nosotros/vosotros

• Wrong: Nosotros duermimos mucho.
• Right: Nosotros dormimos mucho.
• Why: Just like e → ie verbs, the nosotros and vosotros forms keep the original stem vowel because the stress is on the ending.

Forgetting the stem change in stressed forms

• Wrong: Yo dormo ocho horas.
• Right: Yo duermo ocho horas.
• Why: In all stressed forms (yo, tú, él/ella, ellos/ellas), the o must change to ue.

Treating "jugar" as a regular o → ue verb

• Wrong: Thinking jugar has an o that changes
• Right: Jugar changes u → ue: juego, juegas, juega...
• Why: Jugar is unique. Its stem vowel is u, not o, but it still follows the boot pattern.

Not recognizing stem-changing verbs

• Wrong: Treating encontrar as regular: Yo encontro
• Right: Yo encuentro
• Why: You need to learn which verbs are stem-changing. Dictionaries often mark them with (ue) after the entry.

Practice Tips

• Describe your sleep habits. Practice with dormir: Duermo a las once, no duermo bien, dormimos poco.
• Use "costar" when shopping. Ask ¿Cuánto cuesta? (singular) and ¿Cuánto cuestan? (plural) every time you see a price tag, even if just mentally.
• Compare the two boot patterns. Conjugate an e → ie verb and an o → ue verb side by side. Notice that the boot shape is identical, only the vowel change differs.

Related Concepts

• Prerequisite: Regular -AR Verbs