Generally, the best way to locate information on acceptance rates is to visit the journal website and check the author guidelines section.
Another option is to contact the journal editor directly. If the editor won't supply the acceptance rate, ask how many submissions the journal receives a year. Calculate the rejection rate by dividing the number of articles published in that year by the number received. For example, a journal that receives fifty submissions annually and publishes only ten, has a rejection rate of 80 percent (returning 4 out of every 5 submissions), or an acceptance rate of 20%.
Additional resources for locating acceptance rates:
Make sure the journal is indexed in a database, otherwise it will be difficult for others to find your article.
Be wary, too, of disreputable publishers who may falsely claim their journal is indexed in a particular database or with a particular vendor.
Always double check a publisher's claims.
If the publisher tells you that a vendor (EBSCO or ProQuest, for example) indexes the journal--be leery. Vendors like EBSCO and ProQuest produce many different databases; the publisher should provide you with a specific database name.
Find indexing information for your journal in The Serials Directory.
Many professional organizations or societies maintain websites that provide information on their mission, scholarly activities, and publications.
It's a good idea to check the organization/society website to confirm this information, since disreputable publishers may falsely claim their publication is affiliated with a scholarly organization.
Use Google, search the "name of the organization" within quotation marks. Check the website to see if they provide information about their mission, publications, activities.
University or College
Is the journal affiliated with a university? Since predatory journals may list universities as affiliates without the university's permission, check the university’s web site.
Run a Google search of the "journal name" AND "the name of the university". Make sure that the results contain a webpage to the journal originating from the correct university/college URL.