How do you say it has been a long day in french?

There are a few ways to say "it has been a long day" in French, depending on the context and nuance you want to convey:

Formal:

* C'est une longue journée. (This is a long day.)

* J'ai eu une longue journée. (I've had a long day.)

Informal:

* Quelle longue journée! (What a long day!)

* J'en ai assez de cette longue journée. (I'm tired of this long day.)

* C'est pas fini cette journée? (Is this day never going to end?)

* Ça a été une longue journée. (It's been a long day.)

You can also use the word fatigant (tiring) to emphasize the difficulty of the day:

* C'est une journée fatigante. (It's a tiring day.)

* J'ai eu une journée fatigante. (I've had a tiring day.)

The best way to choose the right phrase depends on the situation and your personal style.