Learning English

Meaning and use

We use the future perfect verb form to make educated guesses about things that will happen or that have happened. These predictions are based on what we know now, and are about activities that we expect to be completed by a particular time.

• This time next year, I’ll have finished my course.
• By the time you get back, we’ll have had dinner.
• On their next wedding anniversary, they’ll have been married 50 years.
• We’re still on time: the film won’t have started yet.
• If they’re following their schedule, they will have arrived yesterday.

 The future perfect is often used with a by or in time phrase.

• By 2020 this city will have doubled in size.
• In June, I’ll have been unemployed for three years.

Used in this way, by means up to a stated time. Other by time phrases are: by the summer, by the end of the week, by this time next week/month/year.

We can also use by the time (that) + present simple.

• By the time he arrives, the film will have started.

The expressions … from now or in… time can be used instead of in.

• It’s possible that fifty years from now, scientists will have discovered a cure for cancer.
• It’s likely that in fifty years' time, we will have discovered a new planet.

Take note: future perfect for past?

It may seem strange to use a future form to talk about the past. Remember: the future perfect is based on what you know now - so it's actually a present form. In the present, we don't know with 100% certainty what will happen in the future. We also don't know everything that has happened in the past. However, if we are familiar with the way people behave, timetables and so on, we can expect or assume that certain things have happened, even if we don't know for sure.

• He’ll definitely have got to the airport by now. It only takes an hour.
  I don't know that he has got to the airport. It only takes an hour and I expect he started the journey at the right time.
  
  
• There’s no point in calling Judy. She’ll have left by now.
  I don't know that Judy has left but I expect she has so therefore I can guess that there's no point calling her.
  
  
• If they’re following their schedule, they will have arrived yesterday.
  I don't know for sure that they arrived but I know their schedule. I haven't heard they were delayed, so my expectation is that they arrived yesterday.

Form

Future perfect positive

subject + 'll/will + 've/have + past participle of main verb 

• We’ll have sold the house by Christmas, I’m sure.

Future perfect negative

subject + won’t + 've/have + past participle of main verb

• Rahul won’t have got up yet. It’s too early.

Future perfect questions

Future perfect yes / no questions are made with:

will / won’t + subject + have + past participle of main verb

• Will you have read all the reports by the end of the day?

Question word questions are made like this:

question word + will / won’t + subject + have + past participle of main verb

• How much money will we have made by the end of the year?

Take note: other modals

It’s possible to use other modal auxiliaries instead of will in the future perfect. Different modals show how certain the speaker is about the assumption he or she is making. Remember that the assumption is made on the information the speaker has at the moment of speaking.

Compare:

• By this time next year I’ll have passed my driving test. Quite sure
• By this time next year I should have passed my driving test. Reasonably sure
• By this time next year I may have passed my driving test. Not so sure
• By this time next year I might have passed my driving test. Not so sure

Take note: shall / shan’t

Sometimes, and in more formal situations or in writing, we use shall /shan’t instead of will / won’t with I and we in future perfect sentences.

• We shall have visited all the museums by the time we leave Paris.
• I shan’t have done all my accounts by the end of the month. I’m too busy.

Pronunciation

When using the future perfect when speaking, it’s quite usual to contract the verbs will and have. This means that sometimes the subject + will + have will be combined into one sound of connected speech. So I will have becomes I’ll’ve and you will have becomes you’ll’ve.