Family name Seikaku (Seikaku 
) , all around the world, is a rare surname. The surname Seikaku is characteristic of Japan, where it is a rare surname, and the United States, where it is an extremely rare surname. More prevalently, Seikaku is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Seikaku | Japan, United States |