You need 4 years of undergrad and medical is 4 years. After that it starts to vary based on what you do with residency being anywhere from 3-7 years. The some people go on to do fellowship afterwards which (I think, I haven't really worried myself with them yet) can be 2-3(4?) years. Then if you do a MD, PhD instead of just an MD- Medical School is 6 years instead of 4.