Family name Ridaj (Ridaj 
) , in all the world, is a rare cognomen. The last name Ridaj is characteristic of Slovakia, where it is quite a rare surname, Hungary, where it is a very rare surname, and the United Kingdom. Very seldom, Ridaj is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Ridaj | Slovakia, Brazil, United States, Hungary, United Kingdom |