Can I ask my supervisor how long would it take to complete my PhD before beginning my PhD studies and after getting my acceptance letter? If so, what would be the best way to do so?

Country: US/Canada

Duration: It is not open ended like Europe. Depends on Professor here.

  • 5
    Actually, in some places in Europe there is a strict limit.
    – Buffy
    Commented Apr 14, 2021 at 19:14
  • 29
    You seem to think that if you have done the time, you get a PhD. It doesn't work that way. If there is a time limit, you will be kicked out when time runs out. The time duration of a PhD depends on the student (his/her background), and experience of his/her supervisor. Commented Apr 14, 2021 at 19:24
  • 6
    If you say something about why this question is important to you, I might be able to provide some general advice.
    – Buffy
    Commented Apr 14, 2021 at 19:49
  • 6
    Scientific PhDs in some European countries like France and the UK have quite strict time limits.
    – Mister Mak
    Commented Apr 14, 2021 at 19:53
  • 3
    It would be simpler and best to ask "what is the average time of completion for your PhD students?"
    – Behacad
    Commented Apr 15, 2021 at 15:16

5 Answers 5


This question doesn't really make sense, the supervisor has relatively little control over how long it takes for a student to produce a thesis. Questions you could ask which do make sense:

  1. How long is funding guaranteed, and in practice what happens when students run out of guaranteed funding?
  2. Do you have any additional standards or requirements for a thesis, such as requiring it to include an accepted paper, or requiring it to consist solely of singly-authored material?
  3. How long have your students typically taken to graduate, and what factors played a role in that time?
  4. How does a students career choices effect your advising process?

(The reason the last point is relevant is that if you want a research job it's quite simple, if you have good enough research to get a postdoc and you've actually written pages then you'll graduate. But for a student with teaching or industry career goals there's more flexibility in trying to get a student out more quickly with a more minimal thesis. Some advisors may be more understanding about a student's prioritizing getting out quickly for career reasons rather than produce the most compelling thesis.)


In the US anyways, you are probably best off consulting the program first, rather than the supervisor. PhD programs will typically advertise some statistics on time to completion, like mean/median completion date, and possibly "% complete by ____ years". I would look for this information first.

In most cases PhD durations in the US are indeed open-ended, in contrast to what your question suggests; unless otherwise specified, there will be no strict duration either for an individual advisor or program. There may be upper limits, but most students will strive to graduate well within these limits.

If you do ask your prospective supervisor, I'd start by asking about their past students rather than a prediction (or promise) for you. As mentioned by others and in the comments, PhDs are not about putting a set number of years in and walking away with a degree, they're about taking the necessary time to grow as a researcher and write a suitable thesis. Different people complete the process at different rates. Time limits tend to come as funding runs out and although they can sometimes accelerate process towards a degree (and convince a committee/advisor to help you expedite things a bit) they also represent the point of failure, the date at which you no longer have support to continue and must leave without a PhD. This scenario is not really in anyone's interest: the advisor, the student, the committee, the graduate program all want you to succeed.


You can ask, of course, but don't expect to be able to hold anyone to a definite answer. You should probably just ask for a "typical" time to completion provided that you pass comprehensives. They can tell you with some accuracy how long it has taken other students of theirs, provided they have some supervising experience already.

But if they say three years (or seven), it is very tentative. There can be many delays along the way, which is why I mention comps. And, once you take on a research project, there is no real way to schedule a successful end. That is because research is inherently open ended. Some questions are "too easy" and have no substance and then need to be abandoned. Others are too hard and little progress can be made.

If the supervisor has a lot of experience they can make a better estimate than otherwise, and is probably better at helping you find the right project, but it is up to you to stay focused and make proper progress. But they can't predict with certainty how long you will take because there are too many indeterminate elements.


Definitely good to ask about typical times and what happens if you run over. Note in North America that some forms of funding run out after a certain duration; for instance the department might only guarantee full funding for the expected time of 4 years. Funding agencies may also not accept to pay students much after the expected time.


Yes, you can, but you can't trust him. That's my experience of professors. It takes just as long as he likes, and that depends on your personal qualities and the needs of the lab. Of course, this may be different in the US if the period is limited by the university. Then a good guess is that it takes just as long as it can.

College life is full of as***les, and you should accept that fact, if you embark on this career. Later on, if you make sufficient friends and establish yourself, you can gain success pleasantly fast, but do not accept that in the start of your career.

  • Well, unfortunately, I should agree with you because the things you said are pretty much correct. Commented Apr 15, 2021 at 15:39
  • 1
    Well yes. But you may well encounter similar people in industry as well. And other people doing PhDs won't necessarily have the same (bad) experiences as you. (I didn't!)
    – Stephen C
    Commented Apr 16, 2021 at 7:56

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .