debió
/deh-BYOH/
must have (done something)
When 'debió' means 'must have' (deduction), we visualize someone figuring out a past event based on evidence.
debió(verb)
must have (done something)
?Past probability/deduction
probably
?Implied likelihood
📝 In Action
No contestó el teléfono. Debió estar ocupado.
B1He didn't answer the phone. He must have been busy.
La caída debió doler muchísimo.
B2The fall must have hurt a lot.
Perdió las llaves. ¡Qué despistado! Debió dejarlas en el coche.
B1He lost his keys. How careless! He must have left them in the car.
💡 Grammar Points
Using 'Debió' for Guesses
This form of 'deber' is used when you are making a strong guess or deduction about something that happened in the past. It means 'It is highly probable that...'
Verb Structure
When used for probability, 'debió' is always followed immediately by another verb in its base form (the infinitive): 'debió + comer', 'debió + ver', etc.
❌ Common Pitfalls
Past Obligation vs. Deduction
Mistake: "Using 'debió' (preterite) to express that someone was obligated to do something in the past, but didn't."
Correction: For past obligation that was not fulfilled (He should have studied), use the conditional form: 'debería haber estudiado'. The preterite 'debió' usually implies a strong likelihood that the event *did* happen.
⭐ Usage Tips
The 'Must Have' Trick
Whenever you would say 'must have done X' in English to express a strong guess, use 'debió + [base verb]' in Spanish.
If 'debió' is used in the context of money, it means 'owed' (a debt).
📝 In Action
Ella debió tres meses de alquiler antes de mudarse.
A2She owed three months of rent before moving.
El presidente debió un favor a su equipo de campaña.
B1The president owed a favor to his campaign team.
En ese momento, solo me debió cinco euros.
A2At that moment, he only owed me five euros.
💡 Grammar Points
Debt vs. Duty
When 'debió' is used without an accompanying base verb (infinitive), it almost always means 'he/she/it owed' a debt (money, a favor, an apology).
🔄 Conjugations
indicative
present
imperfect
preterite
subjunctive
present
imperfect
✏️ Quick Practice
💡 Quick Quiz: debió
Question 1 of 2
Which sentence correctly uses 'debió' to express a strong guess about the past?
📚 More Resources
Frequently Asked Questions
What is the difference between 'debió' and 'debía'?
'Debió' (preterite) emphasizes a completed action or a strong, specific deduction (He must have called). 'Debía' (imperfect) refers to a continuous state of obligation in the past (He was supposed to call, but we don't know if he did) or a continuous debt (He always owed me money).
Can I use 'debió' for simple obligation, like 'He had to go'?
While technically possible, native speakers overwhelmingly prefer 'tuvo que ir' (preterite of 'tener que') for simple, completed necessity. Save 'debió' for expressing probability or a financial debt.