Spanish Language Stack Exchange is a question and answer site for students, teachers, and linguists wanting to discuss the finer points of the Spanish language. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top


En ciertas oraciones no sé si es más correcto usar que o de que. ¿Cuáles son las reglas para utilizar que/de que?


Estoy seguro que me fue bien.

Estoy seguro de que me fue bien.


In some sentences I don't know when it is more correct to use que or de que. What are the rules for using que/de que?


Estoy seguro que me fue bien.

Estoy seguro de que me fue bien.

share|improve this question
Great question. Just so you know, using "que" when "de que" should have been used (queísmo) or using "de que" when "que" should have been used (dequeísmo) are common errors even among native speakers. – Diego Mijelshon Nov 15 '11 at 23:03
up vote 22 down vote accepted

There is a simple rule I learned in high school (oh so many years ago) and stuck with me.

You need to replace que and everything after it with eso (which means it), then you will easily see which one is wrong.

Estoy seguro eso (I'm sure it), is wrong.

Estoy seguro de eso (I'm sure of it), is correct.

This helped me from the moment I learned it, up until now that I've written this answer :)

share|improve this answer
+1 This rule is very useful, but more for spanish speakers, who can immediately (by ear) decide if 'eso' or 'de eso' is the correct one. Perhaps it's not so useful for other people – leonbloy Nov 15 '11 at 21:57
That's why I provided a translation which (I think) can be used in a general case for English too. Think "_____ it" and "_____ of it" – juan Nov 15 '11 at 22:00
Thanks @JuanManuel! I've noticed that all my life I have been saying it wrong. – dusan Nov 15 '11 at 23:53
I'm not a native Spanish speaker and this rule has never failed me. English speakers intuitively understand that "Estoy seguro eso" is wrong because "I'm sure that" is wrong in English too (when "that" is being used as a pronoun rather than a conjunction, of course). – Kef Schecter Nov 15 '11 at 23:55
Exactly, the problem is not about "que" and "de que", but rather "seguro de" and "seguro". "Estar seguro de algo" it's a construction, so it always need "de" after "seguro". So in each sentence you have doubts you can use rule mentioned which I didn't know as a native speaker. It seems it should work most times as you will see if the verb need the "de" or not. – JoulSauron Nov 16 '11 at 8:41

The proof of Juan Manual works perfectly but I want to explain why its works.

Some words (can be nouns, adverbs, etc) needs a preposition ("de") before the relative ("que"). The relative, as you maybe know, it's a referencial to the first element that you want modify with a proposition. I'll be more clear with an example:

Estoy seguro de aprobar.

If you replace "aprobar" (that works as a noun) with a proposition:

Estoy seguro de que aprobaré.

You must use "que" because it's the relative of the proposition. So, both of the following phrases are wrong:

Estoy seguro aprobar.

Estoy seguro que aprobaré.

But, too many people in spanish don't "mistake" this. When someone really do a "queismo", if almost because is an overcorrection, they fix a good way to say it.

Returning to the topic, the real proof for an advanced speaker is replace the proposition by a functional word as some pronoun, but the real proof is split the main sentence and detect the proposition and the relative.

share|improve this answer

In Mexican Spanish, que means either "what" or "that" as in a preposition; de que means "of what", as in origin of something and is more of a directional designation of the origin of an object.

share|improve this answer
"Que", "what", and "that" are not prepositions, they are all conjunctions. – hippietrail Nov 17 '11 at 6:55
really, in spanish "que" can be a relative pronoun ("El hombre que me miró", where "que" is "hombre") , an undefinied pronoun ("¡Qué dolor!") or something like (it has a lot of exceptions for a little comment). But in any case, never can't be a conjuction. Conjuctions are used for two or more syntagmas at the same level ("María -y- Juan") and never has a semantic value , while relative pronouns takes a mean or a semantic value, because are joining two elements at different level (a main proposition and a subordinate proposition) – Leandro Tupone Jun 3 '12 at 7:38
Some conjuntions in spanish seems to be a semantical value but they haven't. For eg, "pero", "o", or are constructions that working in a different way has semantical value ("o sea", "sea" is a verb with semantical value but on the conjuction it loses it.). As I said, it seems to be a semantical value but is only a logical value (confrontation, for eg). – Leandro Tupone Jun 3 '12 at 7:41

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.