Journal acceptance rates can be difficult to find. Some journals post their acceptance rates on thier websites, so a quick Google search of the journal title is a good starting place.
The library subscribes to a database called Cabell's that includes acceptance rates for certain journals in certain disciplines. See link on the left.
Occasionally, societies or other parties will publish acceptance rates for journals within a particular discipline. Again, a Google search may help find these. Try keywords like “acceptance rates and biology.”
You can also try to contact the editor of the journal to see if s/he will share the acceptance rate.
When you search for a journal in Bunch Library's OneSearch system, you can view the journal information in SHERPA/RoMEO and SCImago journal ranking.
SHERPA/RoMEO is a database of publishers' policies on copyright and self-archiving.
SCImago provides journal metrics based on citations from the Scopus database.
After selecting a title in OneSearch, look for the links, circled in the image below: