This should be intuitive to use - it requires a data point to estimate off of (e.g. 3.5 is top 25%) and the median gpa. If you don't have the median GPA, use the mean instead (what your school curves to). The estimator assumes that there is a normal distribution, which isn't a perfect assumption, but it's the standard method. I should stress that this will yield only an estimate, though I think it should be fairly accurate (unless you're an outlier of sorts, either high or low. It is likely to be less accurate for outliers).Online Calculator, graciously made by LSATSCORES2012http://mylsn.info/class_rank.phpExcel code:
Open excel and follow these directions:
Cell A1: enter your GPA
Cell A2: enter the median gpa at your school.
Cell A3: enter the GPA of a certain ranked data point (e.g. 3.7 is ~ top 6.8% at UVA, so someone from UVA would enter 3.7)
Cell A4: enter the rank of that GPA (e.g. enter 6.8 if you're at UVA).
Cell A5: copy and paste this formula:
=(1 - NORMDIST(A1, A2, (A3 - A2)/NORMSINV(1-(A4/100)), TRUE))*100
Press enter. Whatever comes up in A5, you're in the top that percentile. You can save the sheet and use it later, as well.
The majority of the replies below are people I estimated for using the manual workaround, until we figured out a way to just put the calculator online. After that there's a little discussion about the calculator and various requests for estimation.