Future Tense in English

1.4. Future Perfect Continuous

We use the future perfect continuous to show that something will continue up until a particular event in the future. We normally use it to emphasise how long something will have been happening for.

Form

The form of the future perfect continuous is will/won’t + have + been + ing (present participle)

Uses and examples

• To show that something will continue up until a particular event in the future. In October, I’ll have been working here for ten years.
• To show something finished just before another time action (cause and effect). When I arrive, I’ll have been working all day, so I’ll be tired.

With time expressions (by + then / tomorrow / next year etc., by the time, when). By the time we arrive, we’ll have been travelling for fifteen hours.