Grammar
Future perfect continuous: describe duration before a future time
Next June, Amina will have been working at the clinic for five years. The sentence looks ahead to June and measures the time that her work will have continued by then.
Use will have been plus an -ing form to describe the duration of an action before a stated future time.
Read and practice
Read the examples and try the written questions in this guide. Listening recordings are not available for this lesson yet.
Try the written questions
will have been working /wɪl həv bɪn ˈwɜːkɪŋ/
The short answer
Use will have been plus the -ing form to show how long an action will have continued before a future time. Include for or since when you want to name the duration or starting point.
By 8:00 p.m., we will have been waiting for an hour.
Why it works: The waiting starts before 8:00 p.m. and has lasted one hour by that future time.
4 more examples
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In September, Amina will have been working at the clinic for five years.
Amina's work began before September and its five-year duration is counted at that future time.
Not this:In September, Amina
will have workedat the clinic for five years. What changes: This also communicates the length of employment. The continuous form is especially useful when the work is viewed as an ongoing activity. -
By the time the guests arrive, I will have been cooking since four o'clock.
Since names the starting point, and the guests' arrival is the future reference point.
Not this:By the time the guests arrive, I
will have cookedthe main dish. What changes: This focuses on completing the main dish, not on the time spent cooking. -
Will you have been driving for long when you reach Leeds?
The question asks about the duration of driving before the future arrival.
Not this:
Will you have reachedLeeds by noon? What changes: This asks whether arrival will be complete by noon. It does not ask how long the journey lasts. -
By next month, the team will have been testing the new system for twelve weeks.
Testing continues over a period that ends at the future reference point next month.
Not this:By next month, the team
will testthe new system. What changes: This predicts a future action but gives no information about its earlier start or duration.
Read the full guide
First, find the future point in the sentence. Then ask whether the speaker is measuring an activity that began earlier and continued up to that point. If the answer is yes, will have been plus an -ing form can make that duration clear.
Look ahead and measure the activity
The future perfect continuous needs a future reference point. It may be a clock time, a date, or another future event. From that point, the speaker looks back at an activity that started earlier and asks how long it will have continued.
By midnight, the technicians will have been repairing the lift for six hours.
Midnight is the future point. Repairing begins earlier and continues for six hours by then.
Next week, I will have been learning Italian for three months.
Next week is the future point, and three months is the measured duration.
Which phrase gives the future reference point: for three months or next week?
Next week gives the future reference point. For three months gives the length of the activity.
Build the form with will have been
Use will have been before the -ing form of the main verb. The helper verbs do not change with the subject: I will have been working, she will have been working, and they will have been working. Do not use will has been or will have working.
He will have been living in Manchester for a year in October.
Will have been is followed by living, the -ing form of live.
They will have been discussing the plan since lunch.
Discussing names the activity that continues from lunch to a later future point understood from the context.
Complete the form: By Friday, she will have been ____ the course. Choose study or studying.
Use studying. The main verb follows will have been in its -ing form.
Use for and since accurately
Use for to give a length of time and since to give the starting point. This distinction stays the same across many continuous tenses. A future reference point tells the listener when that duration is being measured.
By July, we will have been renting this flat for two years.
For two years is a period of time, so for is the correct preposition.
By July, we will have been renting this flat since 2024.
Since 2024 names the beginning of the rental period.
Choose the right word: By noon, I will have been reading ____ 9:00 a.m. Choose for or since.
Use since because 9:00 a.m. is the starting point, not a duration.
Ask questions about duration
To make a question, put will before the subject and keep have been plus the -ing form after it. Questions often ask how long an activity will have continued when another future event occurs.
Will you have been working here for six months when the course begins?
Will comes first because this is a question. The activity is working, and six months gives its duration.
How long will they have been travelling by the time they land?
The question directly asks for the amount of time that travelling will have continued before landing.
Turn this into a question: You will have been waiting for forty minutes by 3:00 p.m.
Write: Will you have been waiting for forty minutes by 3:00 p.m.?
Choose between ongoing duration and a completed result
The future perfect continuous emphasizes the activity and its duration. The future perfect emphasizes that something will be complete by a future point. Both can be possible in a similar situation, but they direct attention to different information.
By Friday, I will have been writing the report for three days.
This stresses the ongoing work and the time spent on it. The report may or may not be finished by Friday.
By Friday, I will have finished the report.
This stresses the completed report. It does not say how long the writing took.
Which form fits a sentence about a finished task by Friday: will have been completing or will have completed?
Use will have completed. The future perfect is the clearer choice when completion is the main point.
Before you go
Remember this
Use will have been plus an -ing form when you want to measure an activity up to a future point. Name the future point, then add for a duration or since a starting time when useful. Choose the future perfect instead when the completed result matters more than the activity's length.
Practice with the written examples
You can practice with the written questions in the Learn tab. Each answer includes an explanation.
Try the written questionsListening test not available yet
This lesson does not have the recordings needed for a listening test. Use the written questions in the guide to check your understanding.
Try the written questionsQuestions about "Future perfect continuous: describe duration before a future time"
What is the future perfect continuous tense?
The future perfect continuous uses will have been plus an -ing form to show how long an activity will have continued before a future time. By 8:00 p.m., we will have been waiting for an hour measures the waiting at that future time.
By 8:00 p.m., we will have been waiting for an hour.
What is the formula for the future perfect continuous?
Use subject + will have been + present participle. For example, In September, Amina will have been working at the clinic for five years. The form is the same with every subject.
By 8:00 p.m., we will have waited for an hour.
When do I use for and since with the future perfect continuous?
Use for with a period of time, as in for two years. Use since with a starting point, as in since 2024 or since four o'clock. By July, we will have been renting this flat for two years gives a duration.
In September, Amina will have been working at the clinic for five years.
How do I make a future perfect continuous question?
Put will before the subject, then use have been and the -ing form. Will you have been driving for long when you reach Leeds? asks about the duration of driving before a future arrival.
In September, Amina will have worked at the clinic for five years.
What is the difference between future perfect and future perfect continuous?
Use the future perfect when the completed result is the main point. Use the future perfect continuous when the activity and the time spent on it matter. Compare a completed report with three days spent writing it.
By the time the guests arrive, I will have been cooking since four o'clock.
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