All over the world, Jannsen (Jannsen 
) is a rare largely male, but seldom feminine forename. The forename Jannsen is habitual in Belize, where it is quite a rare male name, Philippines, where it is a very rare gender-neutral name, and Tanzania, where it is a very rare male name. Not in comparison with a country's population, this name is the most popular in Philippines, Indonesia, and Belize. More frequently, Jannsen is the last name as well as the forename.
| VARIANT | COUNTRY |
|---|---|
| Jannsen | Germany, Indonesia, Philippines, United States, Denmark |
Mr, Karl, Kent, Kees, Kurt, Paul, Piet, Ralf, Rolf, Ryan, Dawn, Dino, Dirk, Gert, Leon, Leif, Lena, Lisa, Lori, Jana, Jann, John, Kara, Joni, Beth, Anna, Ms, Jo, Max, Mia, Kan, Kim, Roy, Dan, Jan, Jed, Jim, Tim, Nic, Ove, Udo, Uwe, Marc, Mary, Sara, Sean, Sven, Anne, and Joan