How many support staff?

only a guide !

It all depends on a lot of factors !

http://techguide.merit.edu/formula.htm

Since all situations are different and support different hardware and software, what we do is actually track time on all the IT staff and on the time to completion for Help Desk tasks. After a while you will get a feel for how many end users each staff member can support. You will also have to include server staff, any programmers and specialists. For example, we have an Electronic Medical Records system that requires 3 1/2 staff members by itself. We also have several thin clients that require very little time to maintain and remote access to almost all systems, so we are able to run 470 users with 3 Help Desk staff while supporting telephones, cell phones, and all the layer 1 work without too much stress. If all your systems are old and problematic or you lack good remote tools you may need more staff.