# How many letters of recommendations is too many [closed]

I am planning to apply for post-doc positions soon. Most universities require three letters of recommendation and most of peers suggested that I should have at least three research letters and one teaching (applying for a research post-doc). My advisor suggested that I have 4 research and one teaching letters. I was not sure if that's too many or the right amount. Any suggestions?

PS: If this question is out of place, please let me know and I will delete it.

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## closed as primarily opinion-based by Najib Idrissi, Shauna, Willie Wong, Andrew D. Hwang, MetaMar 19 '15 at 13:27

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise.If this question can be reworded to fit the rules in the help center, please edit the question.

Twelve is too many. – The Chaz 2.0 Nov 3 '11 at 23:50
$n+1$ where $n = \sup |\{\text{glowing reviews}\}|$. – cardinal Nov 3 '11 at 23:54
@cardinal: determining $n$ seems $NP$-hard to me. – B M Nov 3 '11 at 23:56
Is there any reason that you do not want to follow the advice of your advisor who knows you and your domain? Also, the country might be somewhat relevant for this question. – Phira Nov 3 '11 at 23:56
In that case, you're probably in good shape, anyway. – cardinal Nov 3 '11 at 23:56

## 1 Answer

Speaking as someone at a U.S. institution, my experience suggests that three or four research letters is standard, and fine. Less than three research letters is probably not enough, and if there are many more than four, the file starts to become a bit long to read. However, cardinal's comment above is also important: there is no point diluting your application by adding letters which are not as strong as the existing letters. Of course, you don't know what your letters will say, but as a proxy: once you have three sensibly chosen letter writers, there is no point adding a fourth or fifth if they are not as familiar with you or your work (since the chance that their letters will be weaker, and so dilute your application, is greater than the chance of their letters going the other way).

Of course, your advisor knows all this. But as well as suggesting that you get four letters, hopefully your advisor has suggested four names to write those letters! If so, your advisor probably knows the four suggested letter writers, and is reasonably confident about the letters they will write, in which case I don't think there is any need to go against your advisor's suggestion.

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Thanks for the answer. I will be applying to US institutions (currently at one). My advisor has suggested the names, so I guess I will probably go that route. One of the faculty members here suggested that departments received around 700 postdoc applications. So I just wanted to ensure that the receiving departments does not end up just picking a couple of letters and them turning out to be the weakest of the lot. – B M Nov 4 '11 at 0:09
FYI postdoc applications are often winnowed down to the low double digits before letters are even looked at. If an applicant has no research interests in common with anyone in the department, or is $n$ years out of grad school with no publications, etc, they aren't considered. If someone is bothering to read your letters at all, they are reading all of them. Like everyone says, it doesn't pay to have letters from people who aren't extremely familiar with you (for postdocs, anyway; at the tenure-track level, having more than the required amount is almost always recommended, for other reasons). – leslie townes Nov 4 '11 at 1:02