To complete a bachelors degree, it can take anywhere from 124 -128 credits. This could take approximately four years of study, provided the student takes the program as prescribed by the institution.
I just finished my Bachelor's in Psychology. It actually takes anywhere from 180-195 credits, and does take four years if you are taking 2 classes a semester. If you take on a heavier class load, it is possible to graduate in 3 years.