Family name Густаф (Gustav 
, Gustaf , Gustavs 
) , in all the world, is quite a common cognomen. The family name Густаф is habitual in Namibia, where it is quite a common surname, Cyprus, where it is quite a rare surname, and Sweden. Not in comparison with a country's population, it is the most numerous in Indonesia, Germany, and Spain. More frequently, Густаф is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Gustav, Gustaf | Austria, Germany, Indonesia, Czechia, Sweden |
| Gustavs | Germany, Brazil, Latvia, United States, Sweden |
| Густаф | Kazakhstan, Ukraine, Russia |