Udo's name day is April 12 in Estonia, October 3 in Austria.
Udo is a name of Germanic origin that is primarily found in Central Europe and occasionally in other regions. It is characterized by its short, strong, and masculine sound, projecting a mood that is reliable and deeply traditional. While it is quite rare in the United States, it retains a classic status within its native linguistic territory. The name has a long history of usage, generally perceived as a sturdy and unpretentious identifier for males. It carries a sense of heritage, reflecting naming customs that have persisted through several generations of European history.
| Country | Day | Month | Names |
 Poland | 20 | February | Euchariusz, Eustachiusz, Eustachy, Leon, Ludmiła, Ludomiła, Ostap, Siestrzewit |
| Poland | 1 | March | Albin, Antoni, Antonina, Budzisław, Budzisz, Eudokia, Eudoksja, Ewdokia, Feliks, Herakles, Herkules, Jewdocha, Joanna, Józef, Nikifor, Piotr |
 Spain | 1 | March | Federico, Rosendo, Eudoxia, Eudoxio |
 Estonia | 7 | March | Rudolf, Ruudi, Ruut, Ralf, Rolf, Raul |
 Norway | 27 | March | Rudi, Rudolf |
 Sweden | 27 | March | Ralf, Rudolf |
 Austria | 29 | March | Berthold, Helmut, Ludolf |
| Austria | 17 | April | Eberhard, Rudolph |
 Croatia | 17 | April | Rudolf, Robert |
 Czechia | 17 | April | Rudolf |
 Hungary | 17 | April | Rudolf |
 Latvia | 17 | April | Rudis, Rudolfs, Viviana |
| Poland | 17 | April | Anicet, Innocenta, Innocenty, Jakub, Józef, Klara, Radociech, Robert, Roberta, Rudolf, Rudolfa, Rudolfina, Stefan |
 Slovakia | 17 | April | Rudolf |
| Poland | 7 | May | Benedykt, Bogumir, Domicela, Flawia, Florian, Gizela, Gustawa, Ludmiła, Ludomiła, Sawa, Wincenta |
| Latvia | 27 | May | Dzidra, Gunita, Henrijs, Ludolfs |
| Poland | 21 | June | Albaniusz, Alicja, Alojza, Alojzy, Demetria, Domamir, Marta, Rudolf, Rudolfa, Rudolfina, Teodor |
| Poland | 27 | July | Alfons, Alfonsyna, Aureli, Julia, Laurenty, Lilla, Marta, Natalia, Natalis, Pantaleon, Rudolf, Rudolfa, Rudolfina, Wszebor |
| Poland | 31 | July | Beatus, Demokryt, Emilian, Ernesta, Ernestyna, Helena, Iga, Ignacja, Ignacy, Justyn, Ludomir, Żegota |
 Italy | 25 | August | Ludovico, Vincenzo |
| Slovakia | 25 | August | Ľudovít |
| Spain | 5 | September | Eudosio |
| Slovakia | 14 | September | Ľudomil |
 France | 17 | October | Baudoin, Solène |
 USA | 17 | October | Brad, Braden, Bradford, Bradley, Brady, Braeden, Brayden, Braydon, Rodolfo, Rudi, Rudolf, Rudolph, Rudolphine, Rudy |
| Poland | 2 | November | Ambroży, Bohdana, Bożydar, Eudoksjusz, Małgorzata, Stojmir, Tobiasz, Wiktoryn |
| Austria | 6 | November | Christine, Leonhard, Rudolf |
| Estonia | 9 | November | Teo, Teodor, Tuudor |
| Poland | 10 | November | Andrzej, Lena, Leon, Ludomir, Nelly, Nimfa, Probus, Stefan |
 Denmark | 9 | December | Rudolph |