Cognomen Янчаускас (Янчаускас 
, Janchauskas, Jančauskas 
) , in all the world, is a very rare last name. The cognomen Янчаускас is characteristic of Lithuania, where it is quite a rare surname, Kazakhstan, where it is a very rare surname, and Russia. Not in comparison with a country's population, this name is the most popular in Lithuania, Russia, and Ukraine.
| VARIANT | COUNTRY |
|---|---|
| Янчаускас | Kazakhstan, Russia, Ukraine |
| Jančauskas | Lithuania |