Between 1 to over 100 depending on:
* How well the database was designed and implemented.
* How dynamic the data is (write/edit).
* How many users are Read-Only and how many are Read/Write
users.
* How well your network is configured.
* How busy is your network traffic.
* Power and quality of your hardware.
I tend to stick to under 25 (the max per Access specs is
255) but my thought is mainly how important the database
is to the client. For me, if a database is used by more
than 25 users, it is important enough to have proper back-
up / log / restore procedures.
Put it this way: can you afford to have the database down
for a few hours / a day while X numbers of employees
cannot work efficiently because there is no access to the
database?
HTH
Van T. Dinh
MVP (Access)