The simple future expresses actions that are considered to occur after the moment of speaking and also probable facts or moderate certainties about the future. In many contexts it adds an idea of firm decision, promise, offer, threat or spontaneous resolution. It can also express supposition or probability about the present, especially with verbs like ser, estar and tener.

The regular formation of the simple future is very stable: the same ending is added to the full infinitive of the verb. This rule applies to verbs of the three conjugations and does not require removing the original ending of the infinitive. Therefore hablar, comer and vivir follow the same general pattern.

Several very commonly used verbs change the stem before adding the endings of the future. Among the most frequent are decir, hacer, poder and tener, which form new stems such as diré, haré, podré and tendré. These irregularities also appear in other related forms of the verbal system, so it is worth recognizing them right away.

Other frequently used verbs also present special stems in the future, though they keep the regular endings of the paradigm. They are very important: poner, salir, venir, querer and saber. Learning these basics allows you to quickly form many common expressions of intention and foresight.

The future perfect is formed with haber in the future plus the participle of the main verb. This structure places the action as anterior to another future moment or as completed before a future reference. It is especially useful for expressing anteriority seen from the vantage of the future, as in Future Perfect.

The participle is the non-personal form that accompanies the auxiliary in the future perfect. In regular verbs it usually ends in -ado for the first conjugation and in -ido for the second and third. Its form is learned together with Perfect, Pluscuamperfecto and Future Perfect, because it appears in all of them.

The simple future can often be substituted with going to + infinitive when talking about immediate plans, prior intention, or a very near future, especially in colloquial speech. It also differs from the conditional, which expresses politeness, hypothesis or futurity viewed from the past, so they are not always interchangeable. The simple future also carries a special sense of present probability, something that often surprises learners who come to it from English. For contrasts of aspect and temporal proximity, it is useful to relate it to Present Progressive, Future Progressive, and Simple Conditional.

The simple future brings together prediction, decision, promise, offer, threat, and present probability in a single verb form. Its regular endings are shared by the three infinitive types, but several very commonly used verbs introduce irregular stems. When it appears with haber and the participle, it forms the future perfect and places an action as already completed before another future reference.