Ilo's name day is November 18 in Estonia.
Ilo is a name with deep roots in Finnish and Estonian traditions, often derived from names signifying joy. It’s a relatively rare name in the United States, with limited usage and recognition. Globally, its strongest presence is in Estonia, where it’s traditionally celebrated and recognized. The name is overwhelmingly feminine, historically and culturally associated with girls. Ilo evokes a mood of gentle happiness and quiet strength, suggesting a cheerful and optimistic personality. Its simplicity and distinct sound contribute to its unique appeal.
| Country | Day | Month | Names |
 France | 4 | January | Odilon |
 Greece | 13 | January | Ermilos |
 Czechia | 20 | January | Ilona |
 Slovakia | 23 | January | Miloš |
| Czechia | 25 | January | Miloš |
 Lithuania | 27 | January | Ilona, Jogundas, Jogunde, Natalis, Vytenis |
 Poland | 27 | January | Angelika, Ilona, Jan Chryzostom, Julian, Przybysław |
| Lithuania | 5 | February | Agota, Birute, Gaudvinas, Ilona |
| Czechia | 17 | February | Miloslava |
| Slovakia | 17 | February | Miloslava |
| Greece | 19 | February | Filothei |
 Croatia | 3 | March | Anzelmo, Marin, Kamilo |
 Estonia | 8 | March | Viilup, Viilo, Vilbo, Lepo |
 Latvia | 18 | March | Adelina, Ilona, Razna, Sartite |
| Lithuania | 20 | March | Filomenas, Imgarda, Irma, Tautvile, Zygimantas |
| Estonia | 23 | March | Aksel, Ailo |
| Latvia | 21 | April | Anastasija, Margers, Margonis, Nilola |
 USA | 30 | April | Miles, Milo, Myles, Ryder |
 Bulgaria | 21 | May | Elena, Konstantin, Kosta, Kostadin, Kostadinka, Lenko, Dicho, Lenko, Dinko, Elenko, Eli, Elin, Elka, Ilona, Kojcho, Kostadina, Kostadinko, Kuncho, Stamen, Stanimir, Stanimira, Stanka, Stoil, Stoyan, Stoian, Stoyanka, Trayko, Dinko |
| USA | 1 | June | Brigham, June, Junella, Marilee, Marilou, Marilu, Marilyn, Marylynn |
 Spain | 12 | June | Nazario, Olimpo, Cirilo |
| Spain | 27 | June | Socorro, Zoilo, Ladislao, Anecto, Sansón |
| Lithuania | 5 | July | Butginas, Filomena, Karolina, Mantmile |
| Poland | 5 | July | Antoni, Bartłomiej, Filomena, Jakub, Karolina, Michał, Przybywoj, Szarlota, Wilhelm |
| Spain | 5 | July | Filomena, Filomeno, Zoa |
| Greece | 8 | July | Theofilos, Prokopios |
| Slovakia | 11 | July | Milota |
| Croatia | 14 | July | Kamilo de Lellis, Miroslav |
| Spain | 14 | July | Camila, Vladimiro, Camilo |
| Bulgaria | 20 | July | Iliya, Iliyana, Ilko, Ilina, Ilka, Lilo, Lila |
| Poland | 10 | August | Asteria, Bernard, Bogdan, Borys, Filomena, Laurencjusz, Prochor, Wawrzyniec, Wierzchosław |
| Spain | 11 | August | Clara, Filomena, Susana |
| Estonia | 18 | August | Heleene, Helene, Helena, Elina, Ilona, Helen, Hell, Hella, Helle, Hellen, Helli |
 Hungary | 18 | August | Ilona |
| Lithuania | 18 | August | Gendvile, Ilona, Mantautas, Sailenis, Saulene |
| Poland | 18 | August | Agapit, Bogusława, Bronisław, Bronisz, Helena, Ilona, Klara, Tworzysława |
 Finland | 7 | September | Miro, Arho, Arhippa, Milo |
 Romania | 7 | September | Amfilohie, Simeon, Sozont |
| Spain | 19 | September | Nilo |
| Finland | 9 | October | Ilona |
| Croatia | 8 | November | Gracija Kotorski, Milotislav, Bogdan |
| Greece | 10 | November | Milon, Orion |
| USA | 22 | November | Abbey, Abbie, Abby, Abigail, Cecelia, Cecil, Cecilia, Cecily, Cecyl, Celia, Gael, Gail, Galen, Gay, Gayle, Philemon, Philo, Shayla, Sheila |
| Estonia | 6 | December | Nigulas, Nigul, Nikolai, Niilas, Niilo, Nils, Klaus, Laas, Laus |
| Finland | 6 | December | Niilo, Niko, Niki, Nikolas, Niklas, Nikolai, Niila |
| Romania | 7 | December | Filofteia |
 Austria | 11 | December | Arthur, Damasus, Tassilo |
| Latvia | 14 | December | Auseklis, Dailonis, Gaisma |
| Czechia | 18 | December | Miloslav |
| Slovakia | 27 | December | Filoména |