Tibetan to Gregorian Calendar Converter
The Details
A Tibetan year is properly identified by three parts. The first two, the Animal and Element, correspond roughly to similar identifiers used in the Chinese calendar. The third part is the Rabjung (rab byung, ). The Rabjung are 60-year cycles, the first of which began in 1027 C.E. We are currently in the 17th Rabjung, which began on February 28, 1987.
Unfortunately, pre-modern Tibetan literature doesn't always identify dates with all three of these parts often only the animal and element are explicitly mentioned (and sometimes not even these are given). However, if you can narrow the author's dates to within a century or so, then it's not hard to figure out the rabjung for yourself.
Each year of a Rabjung cycle spans two Western years. This is because the Tibetan New Year or Losar (lo gsar, ) falls in either February or March. You will find a table of Tibetan New Years from 1880 to 1997 in Philippe Cornu's Tibetan Astrology (Boston: Shambhala, 1997), pp. 157-170.
This calculator is based on an algorithm published by Peter Meyer at https://www.hermetic.ch/cal_stud/tib_year.htm.
For more in-depth information about the Tibetan calendar, see http://www.nitartha.org/calendar_overview.html.