In English, the future perfect continuous tense is used to talk about actions that will continue up until a point in the future.[1]https://7esl.com/future-perfect-continuous-tense/
Conjugation
The tense uses the verbs “will”, “have”, “been”, and the present participle (+ing).

When to Use the Future Perfect Continuous Tense
Event that continues up to a specific time in the future
You can use this tense to talk about an event in the future that will continue up to a particular time or event.
For example:
- Susie will
have been working at this company for 5 years by December of this year. - I will
have been studying English for 6
months by the end of this month. - We will
have been living in the same apartment for 3 years by the time we finally
fixed the leak in the ceiling.
Event that just finished before another action or event
You can use this tense to talk about an event in the future that has just finished before something else.
For example:
- I will be tired when I get home this evening
because I will have been working nonstop
for 36 hours. - Susie will be energized on Monday because she will have been relaxing for the previous week on vacation.
- He will be sad because he will have been studying all weekend and not had any time to relax.
Example Exercises
Fill in the blanks with the future perfect continuous tense of the verbs.
How did you do?
If some of these questions were tricky don’t worry — this is one of the topics that confuses English learners the most.
Sometimes reading alone isn’t enough. A private one on one lesson can clear up any confusion quickly and help you use this grammar naturally and confidently.

References
