Last name Buak (Buak 
, บวก 
) , across the world, is a rare cognomen. The last name Buak is habitual in Malaysia, where it is a very rare surname, Indonesia, and the United States, where it is an extremely rare surname. Much less frequently, Buak is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Buak | Indonesia, United States, Malaysia, Philippines, India |
| บวก | Thailand |