Future is used in three different occasions:

• to express future action
• uncertainty about present facts
• probability

To express future action

When talking about future action, the future is replaced with IR + infinitive of the verb in colloquial Portuguese. (The Future tense is mostly used in formal text and in rules and regulations.)

Examples:

With Future

Eu viajarei amanhã

I will travel tomorrow

but instead

Eu vou viajar amanhã

I will travel tomorrow

viajarei = First person future verb form of VIAJAR
vou = First person present verb form of IR
viajar = to travel

97-12-20 IR corrected to VIAJAR, thanks Maria!

What about "I will go..." ?

If you want to say "I will go tomorrow to the beach",
you can't say "Eu vou ir amanhã á praia".

Use either "Eu irei...", using the future tense of the verb, or in colloquial speech use "Eu vou...".

Saying "Eu vou indo..." is only used in very colloquial language. (Indo is gerund of IR.)

 

97-12-20 "eu vou indo" is very colloquial language, use "eu vou", thanks Maria!