How to Ask for Reference Letters for a PhD Application

A PhD application almost always needs reference letters. Some programs call them letters of recommendation. The letters tell the admissions panel how you work, not only what grades you got. Ask for them early, and ask the right people.

Who to ask

Pick people who know your work well. The best reference writer has supervised your research. This can be a thesis advisor, a lab supervisor, or a professor who ran a project with you. Harvey Mudd College's computer science department gives useful general guidance on this choice. A letter from a class teacher is still useful. But it is weaker than a letter from a research supervisor.

Pick people with a PhD, where this is possible. For a PhD application, admissions panels expect your referees to understand research. One strong, detailed letter from a research supervisor is worth more than several short, generic letters.

If you worked in industry before your PhD application, you can still ask a manager for a letter. Pair this letter with at least one academic referee when you can, since PhD panels want to see your research potential.

How many letters you need

The number of required letters depends on the program. The NSF Graduate Research Fellowship Program (GRFP) is a well-known US fellowship. It asks applicants to name three reference writers, and at least two letters must be received by NSF before an application can go in.

Do not guess the number. Check the exact requirement on the program's own application page before you contact your referees.

What to give your referees

Give your referees everything they need to write a strong, specific letter. Harvey Mudd's guidance lists what to prepare:

Your name and the classes or research projects you did together.
A list of the schools or fellowships you apply to, sorted by deadline.
A draft of your statement of purpose or research statement.
An unofficial copy of your transcript.
A list of your relevant experience: research, publications, presentations, and awards.
Your long-term goals, if this is not already in your statement.

The NSF GRFP reference-writer page asks for similar detail from applicants. Tell your referee how you worked together. Point out what you would like the letter to cover. A referee who gets this material can write a more specific, more useful letter.

When to ask

Ask for a reference letter well before the deadline. Harvey Mudd recommends that students give referees their full material by 1 November. This date is for many graduate programs; check each program's own deadline. Arrange for the reference to go in at least three weeks before the application deadline. Online reference systems can take time to set up.

Tip: Ask in person or by a clear, direct email. State the program, the deadline, and why you ask this person. Do not send a mass email to several professors at once.

How to ask, step by step

Make a list of possible referees who know your research or your coursework well.
Contact each person and ask if they can write a strong, specific letter. Accept a "no" without pressure; a hesitant referee may write a weak letter.
Once they agree, send your CV, transcript, draft statement, and the list of programs and deadlines.
Tell your referee which submission system each program uses, and share the request link or form when the program issues it.
Set your own reminder to check, two weeks before each deadline, that every letter has arrived.
Send a short thank-you note after each letter is submitted.

If you apply from another country

Many PhD applicants apply from a country that is not where the program is based. Ask your referee to write the letter in the language the program asks for, usually English. Tell your referee which portal will contact them, since some systems send automatic emails that look like spam. Warn your referee in advance, so they check their inbox and do not miss the request.

If your home university has no formal reference system, ask your referee for a signed letter on official letterhead. Some programs ask for a specific reference form instead of a free-text letter. Check the exact format the program wants before you ask.

A short template for your request

You can adapt this short email to ask a referee:

Dear Professor [Name], I am applying for a PhD position in [field] at [university]. The deadline is [date]. Would you be willing to write me a reference letter? I worked with you on [project or course] in [year]. I can send my CV, transcript, and a draft research statement. Thank you for considering my request.

Keep the email short and specific. State the deadline near the top, so a busy professor does not miss it.

Common mistakes

Do not wait until the deadline is close. Referees need weeks, not days, to write a good letter. Do not ask a referee who does not know your work well, even if they have a famous name. Do not send the same generic request to many professors. Always check the exact number and format each program needs. Some systems only accept a PDF. Some set a page limit.

Where to find open PhD positions

Once your references are ready, you can use them for many applications. Browse open PhD positions on PhD Atlas. Read our guide on how to find a PhD position in Europe. For your other documents, see our guides on the academic CV, the motivation letter, and the research proposal.

PhD Atlas matches open PhD positions to your CV, so you can plan your applications and your reference letters together, well before each deadline.