The overall acceptance rate for RD will be about 6.6%.
“Miller said that while most of the early decision applicants accept their spot — besides three or four students each year who have to reject their acceptance for financial reasons — the University will offer over 2,000 spaces for regular decision applicants. The University expects 30,000 regular decision applicants, he added.”
Deferrals totaled 1905
http://www.browndailyherald.com/2015/12/10/u-admits-22-percent-of-early-applicants/
Of course, each applicant’s chances depend on the strength of their application. Hard for anyone not affiliated with Admissions to be able to say much more.