.............(Think of them as different verbs.)................
These should be treated as two different verbs. In terms of the origin of words, the one verb may have evolved from the other, but, the verbs have different meanings and uses.
SpanishDict is indebted to Lazarus1907 for his frequent, careful discussion and comment on the use and meaning of "ir" and "irse". This Reference Page is entirely based on his thoughtful replies to Forum questions.
|Ir = To go, to go to||Irse = To leave, to leave from|
|"Ir" is an irregularly conjugated verb. It is not idiomatic, not pronominal and not a reflexive verb. "Ir" makes no use of reflexive pronouns.||"Irse" is an idiomatic pronominal verb. While "irse" shares the reflexive pronouns, me, te, se, nos, os, and se, it is not a reflexive verb|
|"Ir" requires a destination. The destination may be clearly stated or may simply be implied. It is said that "ir" focuses on the destination. No starting point needs to be stated or implied||"Irse" requires neither a starting point nor a destination. The starting point for "irse" is always presumed to be here or there where the subject is at the time. "Irse" is focused on the starting point.|
|When "ir" is used, a starting point may optionally be stated. Even so, the focus or emphasis of "ir" is on the destination.||When using "irse", a destination may optionally be stated. Even so, the focus or emphasis of "irse" is the act of leaving or going away.|
|"Ir" is used with prepositions like "a", "hacia" and "hasta" as references to a destination. It is also used to indicate a mode of transportation as in "en tren" or "a pie".||"Irse" is used with prepositions like "de" or "desde" as references to a starting point|
You will be familiar with using "the informal future" which is formed by the verb "ir" plus "a" and the infinitve of another verb. Commonly referred to as "ir + a + infinitive."
"Es mediodía. Voy a almorzar pronto."
(It's noon. I'm going to lunch soon.)
This is dealt with in our Reference page about the future tense found here Future.
Look at this example:
¿Cuando salgo de la sala , cuál es la despedida correcta, 'Tengo que ir.' o, 'Tengo que irme.'?"
(When I exit the room, which is correct for my farewell, 'I have to go' or 'I have to leave'?")
"Tengo que ir" is incorrect. It is a lot like saying "Necesito." In either case a listener would be left to wonder "Tengo que ir....Where?" or "Necesito....What?"
Either sentence is incomplete because no destination on the one hand or object in the other sentence has been specified.
"Tengo que irme.", there is no need to identify where you are going.
If you wish to give a reason for exiting, you might say either
"Tengo que ir a cenar" where the focus is now on your destination, or
"Tengo que irme a la escuela.", where the focus is still on leaving but you have offerred a reason for leaving.
1) Using "irse".
"Me voy" ("I'm leaving").
"Me voy al bar." ("I'm leaving for the bar").
In both these examples, the focus or emphasis is on the act of leaving. In the second case the optional identification of a destination is there, but, the focus is still on leaving.
2) Use of prepositions de or a:
"Me voy de Madrid" ("I'm leaving from Madrid").
"Me voy a Madrid" ("I'm leaving for Madrid").
In these two examples of leaving, you can see the effect that the preposition "a" or "de" has on the translation.
3) "Ir" with a destination only.
"Siempre vamos al cine los viernes." (We always go to the movie theatre on Fridays.")
A destination, the cinema, is stated but there is no information about any starting point.
4) "Ir" with a destination and starting point.
"Vamos de Madrid a Segovia." (We are going from Madrid to Segovia')
The focus is on going to a destination but a starting point has optionally been given.