How old do you have to be to become a CRNA?

Answer:
CRNA = Certified Registered Nurse Anesthetist.

There isn't really a minimum age.

Graduate college @ 22 with BSN.

Minimum 2 years of critical care experience.

2.5 years of CRNA school.
So...

Let's say 26.5 minimum.

That assumes that you go straight into a critical care area as a new graduate, not an easy thing to do,

If you mean CNA (nurse's aide), then 18.

---