How long do you have to go to school to be a sex therapist?

It all depends on your State, county, and city. There are some places in California where you need a minimal of 250 hours, but to be on the safe side, nationally you need 500 hours of training so that you can avoid any difficulties getting a job because of hours completed. I did 500 hours of Massage Therapy in a total of 5 and a half months.