How Long Does a Ph.D. Take?

A Doctor of Philosophy (Ph.D.) is the highest-level academic degree available in the United States. Find out how long it takes to earn this degree, as well as the requirements, coursework, exams, and research.

How Many Years Does It Take to Earn a Ph.D.?

Obtaining a Ph.D. involves completing advanced coursework, as well as passing comprehensive exams and producing a dissertation. Depending on the educational institution and field of study chosen, this process can take five to eight years - or more. This often depends on the field of study, if students are enrolled full or part time, and if they have a master's degree already

Many Ph.D. programs require applicants to already have a master's degree, though some will accept candidates coming straight from bachelor's programs. Master's degree credits can often be applied toward a doctorate, while undergraduate courses must be taken for graduate credit and approved by graduate faculty to count toward a Ph.D.

Program LengthFive to eight years, or longer
Credit RequirementsVaries by program, typically 60-78 credits
Other Requirements Qualifying and/or comprehensive exams
Field of Study Students choose an area of focus based on their interests and career goals
Program FormatCoursework; comprehensive exams; dissertation and defense

How Many Credits Are Required?

Students must complete all required graduate-level coursework to obtain a Ph.D.; however, the exact requirements varies by school and field of study. They are also often expected to participate in colloquia - conferences and seminars - and to maintain a minimum grade point average, such as 3.2 or higher.

The number of credit hours required for a Ph.D. varies. Advanced degrees in education or the humanities usually take longer than those in the hard sciences. For example, a Ph.D. in Microbiology may require about 60 semester hour credits beyond a master's degree, while a Ph.D. in Educational Leadership, Policy & Law requires around 78. Graduate students will often spread out coursework to allow time for teaching and research assistantships that can bring in funding and make them more employable.

What Kinds of Exams Must Students Pass?

Doctoral students are required to pass a series of exams throughout their studies. These are administered over test periods that can last as long as a week, or stretch out over several shorter periods, and often involve both written and oral components. The Ph.D. exam process can include a qualifying exam prior to beginning doctoral work, a candidacy exam during the first year of studies to test ability to proceed, and comprehensive exams upon completion of coursework to ensure that the knowledge has been understood and assimilated.

Students who fail their exams are often given another chance, but repeating the process will extend the amount of time needed to complete a Ph.D.

How Do Students Choose the Focus of Their Research?

While research topics will vary greatly depending on one's discipline, it's important that students select a focus that is something they enjoy exploring and where their aptitude lies, as well as one that will be of interest to other scholars.

While Ph.D. programs often ask candidates to submit a research proposal or to make contact with faculty in their area of interest during the application process, many will require students to develop and defend a prospectus outlining their proposed research prior to beginning their dissertation. Students work closely with a thesis advisor to assist them in this endeavor.

What Is a Dissertation?

Ph.D. students are required to research and write a dissertation, a book-length thesis that demonstrates their knowledge and presents new research in their field. Students work with a dissertation advisor and doctoral committee, usually comprised of 2-5 senior faculty members, to complete their project. Ph.D. candidates in programs that involve fieldwork--such as cultural anthropology or wildlife biology--may take longer to complete their research than those depending solely on academic inquiry.

Once the dissertation is written, candidates defend their project in an oral examination before the doctoral committee. At this time, the committee determines whether or not to award the doctorate and make the candidate's research available to the wider academic community.

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