Jan or Jon
However, if coming from a foreign country to Sweden, you are not expected to spell your name differently. John is ok as it is.
We spell calendar as "Kalender" in Swedish.
Swedish (language) - svenska Swedish (adjective, nationality) - svensk
Cute is "söt" in Swedish.
Brick is "Tegelsten" in Swedish.
leave = "lämna" in swedish
April spells "Aprill" in swedish.
Cup in Swedish spells "kopp".
Twenty five is tjugofem in Swedish.
The number 15 is pronounced as "femton" in Swedish.
The number 33 is pronounced as "trettiotre" in Swedish.
The abbreviation of and, translated into "och" in swedish is "å"
Ampersand translates to et-tecken in Swedish.