Specific times vary by program and student, but a July 2012 CBS Money Watch article indicated that average length of Ph.D. program completion was 8.2 years. Just over half, or 57 percent, of doctoral students complete their degree programs within 10 years.
A primary reason it takes many doctoral students a long time to finish their doctoral work is that they take on teaching, grading and advising tasks with undergraduate students. When considering a Ph.D., it is important for students to weigh career and income opportunities against the years of educational investment. In some fields, such as biology and life sciences, a high percent of doctoral graduates don't get jobs for several years after completion.