We can use the future perfect to say of something that it will have been done by a certain time in the future. Does it make sense to use this tense to tell about something by an undefined time in the future? For instance:

I will have learnt English.

My understanding:

This means that I will have learnt English in the future. It is not defined when exactly I'll have learnt English. This sentence emphasizes a future achievement, not the learning process.

What exactly is the difference in that sentence from future prediction with simple future:

I will learn English.

2 Answers 2


Perfect constructions are relative tenses: the eventuality named by the lexical verb (learn in your example) is located at an Event Time (ET) prior to the Reference Time indicated by the tensed verb (will have in your example) in the construction. The entire construction describes a state at RT which arises out of the eventuality at ET.

Consequently, there must be a definite RT to which ET is related. However:

  1. When we say that the RT must be ‘definite’ we do not require a date/time measure such as tonight or in 2018. RT may also be defined as a particular event, or entry into a particular state. For instance:

    By the time I graduate I will have learnt English.

    As a rule of thumb you may think of ‘definite’ here as meaning “defined enough to recognize it when you see it”.

  2. RT does not have to be defined in the same sentence the perfect occurs in. It may be defined earlier in the discourse; all that is necessary is that your hearer must be able to identify what time you are talking about. For instance:

    I expect to graduate before I am 22 years old. By then I will have learnt English.

    Q: What will you have accomplished by the time you graduate?
    A: I will have learnt English.


I will learn English.

This is generally a commitment. Something you intend to do, whether it is now, or sometime in the future.

  • Now, I will go clean my room.
  • Next year, I will lose weight.

I will have learnt English.

This is more of an expectation than an intention. Rather than committing to learning English here, you are using something else as a reference for the point in time where you learn it. (Often, stating it as a result or consequence of something.)

  • By the time I'm 20, I will have learnt English.
  • After five months of trying, I will have succeeded.

Also worth noting: "I will have ____" does not stand on its own, while "I will ____" can. That is, "I will learn English," is a full and complete sentence, while, "I will have learnt English," is not. (It requires another piece to be a sentence.)

  • That is, "I will have learnt English" even is not grammatically correct? Jul 5, 2014 at 4:27
  • @DmitryFucintv Only when used as a sentence, by itself. As part of a sentence, it is okay, such as in the examples I provided.
    – Cat
    Jul 5, 2014 at 4:28
  • Grammatically, "I will have ___" can stand perfectly well as a sentence on its own, though it usually requires context to make much sense. For example, "What will your skills be by the time you're 20?" "I will have learnt English." Jul 5, 2014 at 11:06
  • @DavidRicherby That's a fair enough point, though to prevent confusion I left it out. Thanks for clearing it up, though.
    – Cat
    Jul 5, 2014 at 16:18

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