To convert your birth year to your Thai birth year is very easy.
All you have to do is take your birth year and add 543.
Example: birth year is 1980
Now add 543
1980 + 543 = 2034 is your Thai Birth Year!
Thailand uses the Thai solar calendar as the official calendar, in which the calendar’s epochal date (Year zero) was the year in which the Buddha attained parinibbāna. This places the current year at 543 years ahead of the Gregorian calendar. The year 2023 CE is indicated as 2566 BE in Thailand.