How long do you have to go to school for a massage therapist?

It really depends on your definition of "therapist." Assuming you mean "psychotherapist", here is a general idea:

All therapists (counselors, social workers, marriage & family therapists, and psychologists) pursue a traditional undergrad degree which is usually 4 yrs.

Here's where it gets tricky! After undergrad one has some choices. Of the choices, you could pursue a masters degree in (counseling, social work, marriage & family therapy, or psychology.) All of these are usually 2-3yrs. BUT!It doesn't stop there. Once you get a masters, then you typically have to work about 3,000 hours(or about 2 years) of supervised work under a licensed practitioner. From here, then you should be eligible to take a state (and in some cases a national exam) to be licensed as a "whatever your degree is in therapist." (If you pass).

Now the other route one can take is to get a doctorate. Most are in Psychology(Phd or PsyD), but there are some in social work and education. In getting the doctorate, one should expect to commit 4-6 yrs of study to complete it(depending on if you have a masters degree). Also, most psychology doctorate grads must complete a 1 yr internship after graduating, which enables one to take the licensing exam to be a psychologist.

So in all, if you go to undergrad that's 4yrs+ A masters degree 2-3yrs+ Depending on if you have a masters degree 4-6 yrs of doctoral work

=about 10-12 yrs in school(+ 1yr for internship if you get a doctorate in psychology) , if you go all the way for a doctorate. If you just want to get a masters and be a therapist then figure about 6-7 yrs+ 2yrs for licensing.