It depend on the school you choose. Each school varies in the number of hours that they offer.
You will have to check with your State Board of massage to find out what number of hours of education are required. Most require at least 500 hours of training which is about a 6 month program.
But that doesn't necessarily mean you can be a successful massage therapist after 500 hours of training.
Massage School only teaches you how to do massage not be a massage therapist.