The personal flag of the King bears the Thai Royal Emblem on a yellow-orange field, i.e. the King's initials B.P.R. (ภ.ป.ร.) underneath the Phra Maha Phichai Mongkut, a chadah-like crown (fig.).

Whilst it is flown throughout the kingdom year round, it is especially seen on display in large numbers on 5 December, King Bhumipon Adunyadet's birthday.

In Thai, the flag is called Thong Nai Luang or Thong Barama Phithai. After the demise of King Rama IX, a similar flag was introduced for King Rama X, i.e. King Vajiralongkorn, who was also born on a Monday and thus according to the sih prajam wan-system, his personal flag also takes a yellow-orange field (fig.).