Tener que y Deber

Tener que y Deber


Tengo que irme - I have to leave

Debo irme - I must leave

I know the difference in English but my students leave me in some doubt about the Spanish versions.

Can anyone explain please?

PS I think they are the reverse in Spanish compared to English.

PPS As with my students I haven't got any clarification yet. (1st June 2010)

In English I think that:

"I must go" indicates that it is better for me to go (for whatever reason)

For example a person will miss their bus if they don't.


"I have to go" indicates that I have an obligation to someone else.

For example a teenager because his parents told him to be home at a certain time

So what is it in Spanish?

I am not asking about "should go" or "ought to go" - that is another can of worms.

updated DIC 2, 2012
edited by ian-hill
posted by ian-hill
irme - Eddy, JUN 1, 2010
Thanks Eddy - ian-hill, JUN 1, 2010

10 Answers


In order of priority of how urgent it is I would say

  1. "Tengo que irme" = I have to go. Now.
  2. "Debo irme" = I must leave. I really must. (but it's not gonna kill me if I don't).
  3. "Debería irme" = "I should leave". But I don't need to. But I should.
  4. "Debo de irme". I should probably go. Possibly. Probably.

Deber DE is new to me though, so I'm not 100 percent on that one though. But I think that's about right. Gracias.

updated JUN 2, 2010
edited by jeezzle
posted by jeezzle
The auto format on this site is so frustrating! - jeezzle, JUN 1, 2010
My post says 1, 2, 3, 4 and yet they all say 1. Why is that I wonder. They are in descending order from 1 to 4. - jeezzle, JUN 1, 2010
I must leave because the ship is sinking. (I will die if I don't ) what about that? - ian-hill, JUN 1, 2010
Ian, probably you won't stand around talking about it; you'll just take off! :-) - Delores--Lindsey, JUN 1, 2010
I think 1 through 3 are correct. I think #4 (debo de) is a common incorrect construct. - tamalmalamarrado, JUN 1, 2010
You know, some of the sites are listing it as incorrect and some list is as correct, I need to ask about it. - jeezzle, JUN 1, 2010

Tamal said:

I think #4 (debo de) is a common incorrect construct.

However, the RAE Diccionario panhispánico de dudas has this to say


  1. Funciona como auxiliar en perífrasis de infinitivo que denotan obligación y suposición o probabilidad:

a) deber + infinitivo. Denota obligación: «Debo cumplir con mi misión» (Mendoza Satanás [Col. 2002]). Con este sentido, la norma culta rechaza hoy el uso de la preposición de ante el infinitivo

b) deber de + infinitivo. Denota probabilidad o suposición: «No se oye nada de ruido en la casa. Los viejos deben de haber salido» (Mañas Kronen [Esp. 1994]). No obstante, con este sentido, la lengua culta admite también el uso sin preposición: «Marianita, su hija, debe tener unos veinte años» (VLlosa Fiesta [Perú 2000]).


  1. tener que o tener de + infinitivo. Ambas perífrasis expresan obligación o necesidad, pero en el español actual solo se usa tener que: «Te agradezco tu invitación, pero tengo que irme» (Mendizábal Cumpleaños [Esp. 1992]). La perífrasis tener de era normal en el español medieval y clásico, pero hoy solo aparece en textos literarios, con intención arcaizante:


a) haber de + infinitivo. En el español general, esta perífrasis denota obligación, conveniencia o necesidad de que el sujeto realice la acción expresada por el verbo —o, si el infinitivo es pasivo, de que le suceda lo expresado por el verbo— y equivale a tener que, fórmula preferida en el habla corriente: «He de reconocer que al principio me incomodó la idea de encontrármelo durante la travesía»

b) haber que + infinitivo. Funciona a modo de perífrasis impersonal y significa ‘ser necesario o conveniente’: «Hay que buscar agua y provisiones»

updated JUN 2, 2010
posted by Izanoni1
Thank you Iza - ian-hill, JUN 2, 2010

As the other answer allude to, deber and tener que are similar but very different when used in sentences. Deber is an auxillary (helping) verb, and means that you should. When you should do something, use deber. For example,

Debo hacer mi tarea, pero no quiero hacerlo~ I should do my homework, but I don't want to do it.

But tener que is a whole different story. Tener que is an obligation, something you must do and that you need to do. For example,

Yo no quiero hacer mi tarea, pero tengo que hacerlo para recibir una buena nota~ I don't want to do my homework, but I have to in order to recieve a good grade.

Hope that helps (:

updated JUN 2, 2010
posted by artsygrl2996
Like your homework examples. - Delores--Lindsey, JUN 1, 2010

What happened to hay que? It is usually included along with these 2 when making contrasts. And I have always heard different versions of which carries the highest and lowest level of obligation.

Tener que, deber, hay que

ought to, have to, should, must....draw an arrow to the corresponding word.

updated JUN 2, 2010
edited by 0074b507
posted by 0074b507

Debo irme can mean I should go, ie not necessarily I must go or I have to go. I think more context is required.

updated JUN 1, 2010
edited by Eddy
posted by Eddy

I have a picture of my self wearing my little sailor hat with water sloshing around my bony knee caps and thumbing through my SD phrase book, ¿tengo irme o debo irme? o debería irme? to heck with it this book is wet I am off. cheese

updated JUN 2, 2010
posted by ray76

Can anyone explain why "Tengo que salir" doesn't work? Or does it?

updated JUN 2, 2010
posted by fasteddy
Yes, "tengo que salir" (I have to go out) works just fine. - --Mariana--, JUN 2, 2010
Thanks yes. For some reason I always think salir simply means "to leave" in that context. Am I wrong in that? - fasteddy, JUN 2, 2010

Sorry but I still have no clarification so I am writing this. grin grin grin

updated JUN 1, 2010
edited by ian-hill
posted by ian-hill

I believe that deber does express obligation, just not as intense of tener que. Look at this link: link text

  1. Tengo que hacer mi tarea. - I have to do my homework.
  2. Debo hacer mi tarea - I must do my homework.
  3. Debería hacer mi tarea - I should do my homework.
  4. Debo de hacer mi tarea - I probably should do my homework (still not sure on this).

As far as I know, deber does imply obligation, but you can remove the obligation with DE or with debería.

I would use Deber for a sinking ship or Tener que. Debo salvarme. Tengo que salvarme.

Edit: That link has some wierd stuff to say about deber de too but wordreference seems to disagree. I would like to hear Gekko's take on Deber + DE + Infinitive VS Deber + Infinitive. I know deber de indicates probability but I am not sure how it affects irse.


updated JUN 1, 2010
edited by jeezzle
posted by jeezzle

Maybe deber implies more of an obligation. Like you, I am curious as to what the subtle differences may be. smile

updated JUN 1, 2010
posted by Delores--Lindsey
Of coutse, this may be because of its similarity to the English word "debt." :-) - Delores--Lindsey, JUN 1, 2010
'course' not 'coutse' - Delores--Lindsey, JUN 1, 2010
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