Leonor, Princess of Asturias, is the elder daughter of King Felipe VI and Queen Letizia of Spain and the first in line to inherit the Spanish throne. Her birthday, 31 October, has become one of the most closely watched dates on the Spanish royal calendar, since it has repeatedly coincided with major constitutional milestones in her life from swearing allegiance to the Constitution at 18 to, this year, the final stretch before her 21st birthday. This article covers everything about Leonor’s birthday: the date itself, how her past birthdays have been marked, and what to expect as she turns 21 in October 2026, shortly after completing both her education and her military training, two milestones that have repeatedly lined up with her October birthday over the past several years.
Quick Facts: Leonor’s Birthday
| Fact | Detail |
| Full name | Leonor de Todos los Santos de Borbón y Ortiz |
| Date of birth | 31 October 2005 |
| Place of birth | Ruber International Hospital, Madrid, Spain |
| Zodiac sign | Scorpio |
| Age (as of August 2026) | 20 years old |
| Upcoming birthday | 31 October 2026 — turning 21 |
| 18th birthday milestone | Swore oath to the Spanish Constitution before the Cortes Generales |
| 20th birthday celebration | Small family gathering at Zarzuela Palace, no gala |
| Grandmother’s birthday | Queen Sofía, 2 November — celebrated two days after Leonor’s |
Who Is Leonor, Princess of Asturias?
Leonor de Borbón y Ortiz is the heir presumptive to the Spanish crown and holds six historic titles, including her primary title, Princess of Asturias. She is the elder of two daughters born to King Felipe VI and Queen Letizia; her younger sister, Infanta Sofía, was born in 2007. Readers interested in the full list of titles she holds can find a complete breakdown in our companion article, Leonor, Princess of Asturias: Her Full Royal Titles.
Because Leonor is set to become Spain’s first queen regnant in over 150 years, her birthday carries more institutional weight than an ordinary royal birthday; it is the date against which several of her most significant public milestones have been measured.
When Is Princess Leonor’s Birthday?
Leonor was born on 31 October 2005 at the Ruber International Hospital in Madrid, making her a Scorpio by zodiac sign. She was born three weeks before her due date, via a caesarean section made necessary by non-progression of labour, and was the first child born to then-Prince Felipe and Princess Letizia of Asturias, who had married in May 2004.
- Date: 31 October (Halloween in much of the world, though not widely marked as such in Spain).
- Year: 2005, meaning she turns 21 in 2026.
- Notable overlap: her birthday falls just before Spain’s All Saints’ Day holiday on 1 November.
- Family overlap: her grandmother, Queen Sofía, celebrates her own birthday two days later, on 2 November.
Her 18th Birthday: A Constitutional Milestone
Leonor’s 18th birthday, on 31 October 2023, was unlike almost any other birthday marked by a European royal heir. Rather than a private or purely ceremonial celebration, it was structured around a formal constitutional act: a public oath of allegiance to the Spanish Constitution, delivered before the Cortes Generales, Spain’s Parliament.
- Location: the Palace of the Cortes Generales in Madrid.
- Act performed: a formal oath of allegiance to the Spanish constitution and the king.
- Honour received: the Collar de la Real y Distinguida Orden Española de Carlos III, presented afterward at the Royal Palace of Madrid.
- Attendance: her parents and younger sister, Infanta Sofía, who returned briefly from school in Wales for the occasion.
In her remarks around the ceremony, Leonor said she was aware of the responsibility the day represented, noting that from that point on she owed herself “to all Spaniards, whom I will serve at all times with respect and loyalty”. The ceremony took place amid some political controversy, with a small number of left-leaning and separatist politicians boycotting the event, a reminder that even a birthday milestone for the heir carries real political weight in Spain.
Her 20th Birthday: A Quiet Family Celebration
By contrast, Leonor’s 20th birthday on 31 October 2025 was reported to be a deliberately low-key, private family affair, a sharp contrast to the formal constitutional ceremony two years earlier. At the time, she was in the midst of her military training at the General Air and Space Academy in San Javier and required permission from the academy to spend the weekend in Madrid for the celebration.
- Setting: a small family gathering at Zarzuela Palace, possibly held in the gardens.
- Food tradition: a chocolate cake, reportedly a shared favourite of Leonor and her grandmother, Queen Sofía.
- Guests: close family, with dietary preferences such as Infanta Cristina’s pescetarian diet accommodated on the menu.
- No gala: reports noted Leonor was in no hurry to debut a formal tiara, keeping the occasion relaxed rather than ceremonial.
The timing was notable for another reason: because her birthday fell on a Friday in 2025, it marked one of the first times in years that Leonor could celebrate at home with family and friends, rather than around a packed public schedule.
Her 21st Birthday: What to Expect in October 2026
Leonor turns 21 on 31 October 2026, just months after completing her three-year military training in July 2026 and shortly before she is expected to begin her political science degree at Carlos III Public University in Madrid. Unlike her 18th birthday, this milestone carries no formal constitutional requirement, meaning it is likely to follow the more private, family-orientated pattern seen on her 20th birthday rather than a return to public ceremony.
That said, royal commentators have noted that her 21st birthday arrives at a symbolically significant moment: the close of her structured military and educational preparation and the beginning of a phase in which she is expected to take on a steadily larger, more independent public role.
How the Spanish Royal Family Typically Celebrates Birthdays
Compared with some other European monarchies, the Spanish Royal Household tends to keep birthday celebrations for its younger members relatively modest and private, reserving large public ceremonies for milestones with genuine constitutional significance, such as an 18th birthday oath of allegiance.
- Milestone birthdays (18th): marked with a formal public ceremony and constitutional significance.
- Standard birthdays: typically private family gatherings at Zarzuela Palace, rarely publicised in detail beforehand.
- Shared family dates: celebrations are sometimes clustered around related family birthdays, such as Queen Sofía’s, which falls just days after Leonor’s.
This approach reflects a broader pattern in how the Spanish monarchy presents itself: emphasising institutional duty and restraint over lavish public celebration, even for significant personal milestones.
Notable Birthday Traditions and Family Details
A few small, recurring details have emerged from reporting on Leonor’s birthdays over the years, offering a rare glimpse of her more personal, private side, away from the formality of state ceremonies and public engagements.
- Chocolate cake is a favourite shared with her grandmother, Queen Sofía, and reportedly inherited from her father, King Felipe VI.
- Family buffets are small, informal meals at Zarzuela Palace adapted to guests’ dietary preferences rather than large formal banquets.
- Outdoor settings: weather permitting, celebrations have reportedly been held in the palace gardens.
- Close timing with Queen Sofía’s birthday, the two celebrations, two days apart, are sometimes marked together as a family occasion.
Her Birthday in the Context of Her Education and Training
Leonor’s birthday has repeatedly lined up with major turning points in her broader preparation for the throne. Her 18th birthday marked the formal end of her time as a minor and the beginning of her constitutional role as heir; her 20th birthday fell in the middle of her military training at San Javier; and her 21st birthday follows immediately on the heels of completing that training and moving toward university study, detailed further in our article on her education.
This overlap is not entirely coincidental: because Spain’s heir traditionally begins military training shortly after finishing secondary school and continues it for roughly three years, the structure of her education and training was always going to intersect with her birthdays at 18, 20, and 21, turning what might otherwise be a purely personal date into a recurring marker of her institutional progress.
It is a pattern likely to continue even after her 21st birthday: with full military commissions expected in 2027 and university study now underway, each subsequent birthday is likely to double as an informal progress report on both fronts, much as it has for the past three years.
Why Leonor’s Birthday Draws Public Attention
Public interest in Leonor’s birthday goes well beyond simple curiosity about a royal figure’s age. Because she is expected to become Spain’s first queen regnant in over 150 years, each birthday functions as an informal checkpoint on her path to the throne, prompting retrospectives on her life so far and speculation about what comes next in her public role.
This pattern is likely to continue for the foreseeable future, with each birthday offering a natural occasion for Spanish and international media outlets to revisit her education, titles, military service, and gradually expanding calendar of official duties.
There is also a comparative element to the attention: royal watchers frequently place Leonor’s birthdays alongside those of other young European heirs, such as Princess Ingrid Alexandra of Norway, Princess Elisabeth of Belgium, and Princess Catharina-Amalia of the Netherlands, all of whom are navigating similar transitions from adolescence into adult public life around the same period. This generational comparison has made coverage of Leonor’s birthday part of a broader, ongoing conversation about how modern European monarchies are preparing their next generation of heirs.
Frequently Asked Questions
When is Princess Leonor’s birthday?
Her birthday is on 31 October. She was born on 31 October 2005 in Madrid, Spain.
How old is Princess Leonor?
As of August 2026, she is 20 years old. She turns 21 on 31 October 2026.
What happened on Princess Leonor’s 18th birthday?
She swore a formal oath of allegiance to the Spanish Constitution before the Cortes Generales and received the Collar de la Real y Distinguida Orden Española de Carlos III.
How did Princess Leonor celebrate her 20th birthday?
With a small, private family gathering at Zarzuela Palace, reportedly including a chocolate cake, rather than any formal public ceremony.
Is there a special ceremony for Princess Leonor’s 21st birthday?
No formal constitutional ceremony is expected. Her 21st birthday is likely to follow the more private, family-orientated pattern of her 20th.
Whose birthday is close to Princess Leonor’s?
Her grandmother, Queen Sofía, celebrates her birthday on 2 November, just two days after Leonor’s.
Conclusion
Leonor’s 31 October birthday has become far more than a private family date; it has repeatedly marked significant turning points in her life, from her constitutional oath at 18 to the quiet family celebration in the middle of her military training at 20. As she turns 21 in October 2026, closely following the completion of her military service and just ahead of her university studies, her birthday continues to serve as a useful marker of just how far along Spain’s future queen has come in her long, carefully structured preparation for the throne.
References
HOLA! “Princess Leonor celebrates her 20th birthday with surprises and family moments.” (October 2025) https://www.hola.com/us/royals/20251031864930/princess-leonor-20th-birthday-surprises-family-moments/
Hello Magazine. “20 Facts about Princess Leonor to celebrate the future Queen’s 20th birthday.” https://www.hellomagazine.com/royalty/863959/princess-leonor-spain-celebrate-20th-birt (October 2023) https://www.hola.com/us/royals/20231030352051/princess-leonor-spain-18th-birthday-celebration/
BBC News. “Princess Leonor of Spain’s royal profile rises as she turns 18.” https://feeds.bbci.co.uk/news/world-europe-67230053
Reuters (via Inquirer). ” Spain’s Princess Leonor swears allegiance to divided nation on her 18th birthday. ” https://newsinfo.inquirer.net/1853499/spains-princess-leonor-swears-allegiance-to-divided-nation-on-her-18th-birthday
Wikipedia. “Leonor, Princess of Asturias.” https://en.wikipedia.org/wiki/Leonor,_Princess_of_Asturias
About the Author
This article was researched and written by the Royals & Culture Desk, a team focused on producing accurate, up-to-date explainers on European royal families, their history, and their public roles. All facts in this piece were verified against publicly available sources, as of August 2026.
