NEPAL - Please use the link: https://english.hamropatro.com/calendar/2057/8
Just select the date, month, and day to see the conversion. (the month on the client's ID is the Nth month on the drop-down counting from top to bottom)
THAILAND - please use this link: https://thaiwithgrace.com/thai-year/.
Just type in the year to convert in the "Thai Year" field.