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 |
|---|---|
| Gustaf, Gustav | Czechia, Germany, Indonesia, Sweden, Austria |
| Gustavs | Germany, Sweden, United States, Brazil, Latvia |
| Густаф | Kazakhstan, Russia, Ukraine |