Leen's name day is July 22 in Estonia.
Leen is a name gaining traction in the US, while being more established in Dutch and Flemish-speaking countries like Belgium and the Netherlands, and Estonia. It often functions as a shortened form of names like Helena or Marlene, but also stands alone. The name’s history reflects a trend towards concise naming practices, and its mood is generally perceived as gentle and strong. While predominantly feminine, it can be masculine in some regions, particularly in the Netherlands. Leen’s simplicity and modern sound contribute to its increasing appeal.
| Country | Day | Month | Names |
 USA | 1 | January | Arleen, Arlen, Arlene, Arlette, Pablo, Paul, Saul |
| USA | 28 | January | Carlotta, Charleen, Charlene, Charlotta, Charlotte, Charmaine, Manfred |
| USA | 23 | April | Brayan, Breana, Breanna, Breanne, Brian, Briana, Brianna, Brianne, Brielle, Brien, Briona, Bryan, Bryana, Bryanna, Bryant, Brynn, Bryon, Shirlee, Shirleen, Shirley |
| USA | 22 | May | Jolee, Joleen, Jolene, Jolie, Marshall |
| USA | 25 | May | Madalyn, Madeleine, Madeline, Madelyn, Madilyn, Marlee, Marleen, Marlena, Marlene, Marley |
| USA | 28 | June | Dara, Darla, Darleen, Darlene, Darrell, Darren, Darrin, Darryl, Daryl, Jarell, Jerrell |
 Finland | 22 | July | Leena, Leeni, Lenita, Matleena |
 Estonia | 18 | August | Heleene, Helene, Helena, Elina, Ilona, Helen, Hell, Hella, Helle, Hellen, Helli |
| USA | 18 | August | Aileen, Eileen, Elaina, Elaine, Eleanor, Elena, Eliana, Ella, Elle, Ellen, Ellie, Helen, Helena, Iliana, Lena, Leonora, Nell, Nellie, Nelly |
| USA | 12 | November | Colan, Colin, Colleen, Collin, Cullan, Cullen, Culver, Kiley, Kyla, Kyle, Kylee, Kyleigh, Kyler, Kylier |
| USA | 25 | November | Caitlin, Caitlyn, Carina, Caryn, Catherine, Cathleen, Cathy, Kaitlin, Kaitlynn, Kara, Karen, Kari, Karina, Kate, Katelyn, Katelynn, Katharine, Katherine, Kathleen, Kathryn, Kathy, Katie, Katrina, Treena, Trina, Trinity |