A letter of recommendation for graduate school is the one part of your file that someone else writes. The decisions around it are still yours: who writes, when you ask, and whether you give up the right to read it. Stanford Graduate Admissions states the most common rule plainly: “Three letters of recommendation are required for your application.”
The answers below come mainly from eleven graduate schools and programs, read on October 16, 2026, for fall 2027 entry where a page names its cycle. How to word the request to a professor is a topic of its own, and law, MBA and medical school letters are not covered here.
Key Takeaways
- Nine of the eleven schools and programs in our table ask for three letters as standard. Duke’s Graduate Liberal Studies and two Tufts master’s programs ask for two.
- Professors lead the lists, but Harvard Kennedy School moves two of its three letters to work colleagues after more than two years of work.
- Five of the eleven want letters by the application deadline. Tufts allows two weeks after it.
- Harvard Griffin GSAS and Stanford refuse letter services such as Interfolio; Berkeley, UChicago English and Iowa English accept them.
- Decide on the FERPA waiver before you send each request: MIT locks the answer once the request goes out.
The Number of Letters Graduate Programs Ask For
Three is the most common count on these pages, but each school or program sets its own. Harvard Griffin GSAS “requires three letters of recommendation.” The Duke Graduate School asks for three too, except that “Applications for Graduate Liberal Studies require only two recommendation letters.” MIT’s Office of Graduate Education says “Most departments require 3 letters of recommendation.”
Tufts’ graduate admissions office spells out its exceptions in an August 2026 post for the 2027 application. Its Graduate School of Arts and Sciences and School of Engineering generally ask for three, “although some programs require two (such as our Biomedical Engineering MS and Chemistry MS).” UC Berkeley’s Graduate Division names no number: “The application requires letters of recommendation. Please check with your program of interest for questions.”
Here is how the eleven compare, in each page’s own terms.
| School or program | Letters | Who the page asks for | When letters are due | Cycle |
|---|---|---|---|---|
| Stanford Graduate Admissions (all programs) | Three required; up to four listed | Academic or professional references; at least one professor strongly recommended | Same as the application deadline, unless the program says otherwise | Read October 16, 2026 |
| Stanford English PhD | No more than three | Current or former professors in your major-field courses | May arrive after the deadline; review starts soon after it | 2027-28 (deadline December 1, 2026) |
| Harvard Griffin GSAS | Three required | Faculty or others qualified to judge; one from your most recent school unless out of school over five years | By the program's application deadline | Read October 16, 2026 |
| Harvard Kennedy School master's programs | Three; extras not accepted | Two faculty and a supervisor (encouraged), or two work colleagues after more than two years of work | All required materials by December 1, 2026, noon ET | 2027-2028 |
| Duke Graduate School | Three (two for Graduate Liberal Studies) | Academic references in your major field preferred | No date on its letters page | Read October 16, 2026 |
| MIT | Three in most departments | No type asked for; applicants are judged on letters from "individuals familiar with their capabilities" | Most departments lenient on late letters; check yours | Read October 16, 2026 |
| UC Berkeley Graduate Division | Set by each program | No type named on its requirements page | System accepts letters after the deadline; check the program | Fall 2027 |
| Tufts (Arts and Sciences, Engineering) | Generally three; two in some programs | Professors, mentors, supervisors or colleagues who know your work | Up to two weeks after the program deadline | 2027 application |
| USC Psychology PhD | Three | Professors or supervisors | December 1, 2026 (November 9, 2026 for clinical science priority) | Fall 2027 |
| KU Anthropology (MA and PhD) | Three | Faculty members or others who know your work well | No letter date apart from the December 2, 2026 deadline | Fall 2027 |
| Iowa English (MA and PhD) | Three | Instructors of your college English courses, or professionals who know your writing | All documents by December 14, 2026, 4:00 p.m. CST | Fall 2027 |
Three of these schools cap or discourage extras. Harvard Kennedy School says “Additional letters will not be accepted,” Stanford’s English department says “You should submit no more than three letters,” and Duke warns that “an excessive number of recommendation letters may actually cause application reviewers to view your file unfavorably.” Duke strongly discourages requesting more than three “unless you are asked to do so by the department to which you are applying.”
Harvard Griffin GSAS allows extra letters but says “it is not guaranteed that the admissions committee will review additional letters.” Stanford’s FAQ lets you list a fourth recommender “to serve as a backup in case one of your first three recommenders is unable to submit by the deadline.” UChicago’s English PhD asks for “3-4 confidential letters of recommendation.”
Who to Ask for a Letter of Recommendation for Graduate School
Academic writers come first on these pages. The University of California’s graduate admissions site says “Generally, all your letters should be from professors,” though “a letter from your mentor or supervisor also may be helpful” if you have done research or worked in the field. Stanford takes “academic or professional references who know you well” but strongly recommends at least one university professor. Harvard Griffin GSAS wants one letter from a faculty member at the school of your most recent degree, unless you have been out of school more than five years.
Work experience changes the mix at Harvard Kennedy School, the one professional school in our table. Harvard Kennedy School’s master’s admissions page splits it this way:
- Undergraduates, or under two years of work (encouraged): “two letters of recommendation from university faculty members and the third from your immediate supervisor from a professional work environment or internship.”
- More than two years of work: “two of your three letters of recommendation should be from current or previous work colleagues, including a supervisor,” with an academic reference encouraged if possible.
Field shapes who qualifies, too. USC’s Psychology PhD wants “professors or supervisors familiar with your potential for graduate training and professional contributions to psychology.” Iowa English prefers instructors of your college English courses or professionals who know your writing, and KU Anthropology asks for “faculty members or others with whom you have worked and who know your work well.” Tufts sums up the test: “Focus on someone who knows your work well, rather than someone based simply on their title or position.”
When to Ask, and When Letters Are Due
The pages that address lead time put it differently. Texas State University’s Graduate College says “We would suggest asking your recommender 3-4 weeks before the deadline.” Tufts says to “Reach out several weeks before your application deadline, or earlier if possible.” Stanford tells you to register recommenders “as early as possible to ensure their letters are received by the application deadline.”
Ask before you enter a name in the application. Texas State explains why: when a system emails recommenders automatically, “it is common courtesy to request their recommendations before entering their contact information.” Harvard Griffin GSAS likewise asks you to confirm that your three recommenders have agreed before you apply.
Due dates fall into three groups:
- By the application deadline: Stanford Graduate Admissions (unless a program sets another date) and Harvard Griffin GSAS. Harvard Kennedy School wants all required materials by December 1, 2026, at noon ET for 2027-2028. USC Psychology’s date is December 1, 2026, or November 9, 2026 for its clinical science priority deadline. Iowa English wants every document, the statement of purpose included, by December 14, 2026, at 4:00 p.m. CST.
- A short window after it: Tufts asks for letters within two weeks after the program’s deadline.
- Late letters accepted, with a warning: Berkeley’s system takes them, and its Graduate Division FAQ adds “Please check with the program you are applying to regarding their recommendation deadline requirements.” MIT says most departments grant leniency. Stanford attaches late letters, but “late letters are not guaranteed to be reviewed,” and Stanford’s English PhD begins reviewing soon after the deadline.
Give your recommenders what they need to write. Tufts says to provide “your program information, application deadline, résumé or CV, and any other information that may help them understand your goals and accomplishments.” If your CV or statement is still a draft when you ask, ExceptionalGrad’s graduate application advisors “will review your application, help edit essays, optimize your C.V., and assist with interview preparation,” in the page’s words.
How Recommenders Submit Their Letters
Ten of the eleven schools in our table describe letters going through the school’s own online system; KU Anthropology’s page does not cover the step. At the eight that describe the request step (Stanford Graduate Admissions, Stanford English, Harvard Kennedy School, Duke, MIT, Berkeley, Tufts and Iowa), you enter each recommender’s details and the system emails them a link.
Letter services such as Interfolio split the six schools that address them:
| School or program | Letter services (Interfolio and similar) |
|---|---|
| Harvard Griffin GSAS | Not accepted: no letters "via email, mail, or a dossier service" |
| Stanford Graduate Admissions | Not accepted: recommenders answer evaluation questions on Stanford's form |
| Stanford English PhD | Not accepted: its system "does not work directly with the letter service (such as Interfolio) process" |
| UC Berkeley Graduate Division | Accepted, using the Interfolio-generated email address in place of the recommender's |
| UChicago English PhD | Accepted: "you may use a service like Interfolio" |
| Iowa English | Accepted, with the service emailing the letters to the address on the admissions page |
MIT adds one more rule: “Letters of recommendation cannot be shared between multiple applications.”
The FERPA Waiver: Whether You Can Read Your Letters
Each request comes with a question: do you waive your right to see the letter? Harvard Griffin GSAS explains that “By law, enrolled students have the right to view their letters of recommendation unless they indicate otherwise at the time of application,” and MIT notes that “FERPA rights extend only to enrolled students.” Berkeley calls waiving voluntary and puts the choice on each invitation.
Stanford’s FAQ says waiving “lets your recommender know that you do not intend to read the letter,” which reassures the committee that the letter is “candid and truthful.” Declining has a cost at two schools. At Stanford, “your recommender may decline to provide a letter,” and MIT says “Some recommenders will not write a letter of recommendation unless the applicant waives their right to view.”
Settle the answer before the request goes out. MIT locks it once your recommenders receive the request email or you submit, whichever comes first, and calls the waiver “a personal choice” to weigh “in collaboration with your recommenders.” At Stanford, changing it means excluding the request and adding the recommender again.
What a Strong Recommendation Letter Covers
Your recommender writes the letter, and several schools tell them what to cover. Stanford’s general prompt asks the writer to address the applicant’s “potential to carry on advanced study in the field specified, intellectual independence, capability for analytical thinking, ability to organize and express ideas clearly, and potential for teaching.” Berkeley asks recommenders for “personal impressions of your intellectual ability, your aptitude in research or professional skills, your character, and the quality of your previous work and potential for future productive scholarship.”
Some schools add a rating form to the letter. Stanford’s asks the writer to name a comparison group and place you in it, from “Top 1-2%” to “Bottom quarter.” Harvard Kennedy School’s form rates you in several areas, “including intellectual ability, leadership, and problem-solving orientation.”
For the shape of the letter, the University of Chicago’s Career Advancement office gives faculty an outline for job and graduate school letters. Summarized, its parts after the salutation are:
- Introductory paragraph: who the writer is, how they know you and for how long, and two or three strengths.
- Two or three body paragraphs: the strengths developed with one or two specific examples and anecdotes, compared with peers where that fits.
- Closing paragraph: the strengths restated and support for the candidacy repeated.
- Signature: name and title.
If your recommender wants a model, our letter of reference template annotates what each of its four paragraphs has to prove. Do not write the letter for them, even if they ask. Stanford is explicit: “Drafting, writing, translating, or submitting your own reference, even if asked to do so by a recommender, is a violation of our application terms.”
Frequently Asked Questions
Do grad school letters of recommendation have to be from professors?
No. Stanford’s English PhD says that when professors are no longer available, “anyone who you think can best assess your potential for graduate study can be asked to write the letter.” Stanford Graduate Admissions, Harvard Griffin GSAS and Duke still ask for or prefer at least one academic letter, as read in October 2026.
Can you submit a grad school application before letters of recommendation?
Yes, at Berkeley, Harvard Griffin GSAS, MIT, Stanford and Tufts (read October 2026). MIT and Tufts want recommenders named first: MIT does not let you add recommenders after you submit, and Tufts lets you submit with letters pending once the required number is registered. Berkeley lets you add recommenders after submitting until a letter arrives.
How long should a letter of recommendation be for graduate school?
None of the graduate school pages we read in October 2026 sets a length. UChicago’s Career Advancement office, writing for faculty, says “1 page is a good target length for most letters of recommendation unless otherwise specified by the employer.” Stanford’s prompt asks for content: actions, accomplishments, character and personal qualities tied to scholarly achievement.
How much do letters of recommendation matter for grad school?
At the two English PhD programs we read, they rank near the top. Stanford English says “Heavier emphasis is placed on the writing sample and letters of recommendation,” and UChicago English counts recommendation letters among the materials “of most relevance.” Berkeley’s Graduate Division weighs them alongside statements, academic record and test scores (read October 2026).