The NACADA 2011 national survey of academic advising addressed, among other things, caseload issues. Chapter 6 is comprised of data from US members in chart format that breaks professional advisor load data down by institutional type.
We also have an advisor load implications article authored by Rich Robbins here: http://www.nacada.ksu.edu/Resources/Clearinghouse/View-Articles/Advisor-Load.aspx that gives some context and how best to begin assessing your own institution’s needs.
Should you still need information around current practice, then you may query the advising administrator listserv. Find subscription information at https://www.nacada.ksu.edu/Resources/Listserv-Mailing-Lists/Advising-Administration.aspx
If you would prefer not to subscribe to an email list, then the Advising Admin Community has a Facebook group here: https://www.facebook.com/groups/advisingadministration/. You could opt to join and then post your question.
NACADA does not have a suggested ratio since advising duties vary by institution type and the purpose(s) of the advising office. The CAS Standards of Academic Advising state that "Academic advising caseloads must be consistent with the time required for the effective performance of the activity" https://www.nacada.ksu.edu/Resources/Clearinghouse/View-Articles/Using-CAS-Standards-for-self-assessment.aspx Eric White, a NACADA past-president and former NACADA representative to CAS, states that in considering caseloads "an institution must take into account
- (1) what kinds of students are to be advised and consequently what are their advising needs (e.g, athletes, honor students, undecideds, seniors in majors, underprepared students);
- (2) Who is providing the advising (professional staff with no other responsibilities, faculty with teaching and/or research responsibilities, graduate students); and
- (3) what other responsibilities would an advisor have that might determine an appropriate 'case load.'"
You can find the median number of advisees per advisor for a full-time advisor is 296 students (as listed in the NACADA 2011 Survey). Also in the Clearinghouse is an overview by Rich Robbins, who discusses the issues surrounding how to determine the right advisor/advisee ratio for your institutional set up. Find this overview at http://www.nacada.ksu.edu/Resources/Clearinghouse/View-Articles/Advisor-Load.aspx.
Additionally, the implications article written by Casey Self in response to these findings http://www.nacada.ksu.edu/Resources/Clearinghouse/View-Articles/Implications-of-advising-personnel-of-undergraduates-2011-National-Survey.aspx. In the Clearinghouse section of the NACADA web you will find the Organizational Structures Index and it is here that we can provide for you articles and additional resources to best practices for Advisor Caseloads here: https://www.nacada.ksu.edu/Resources/Clearinghouse/Organizational-Structure.aspx