Most people spend about 4 years in college getting their bachelor's degree. From there, the amount of time it takes depends on what you want to do. If you want to become a faculty scientist at a research university, you need a PhD, which will take an additional 5 or 6 years after college. However, if you get a job as scientist at a lab or company, then you may need only a Master's degree which often takes 2-3 years, so can get you into a job even sooner.