The age distribution, , in Belmont-sur-Lausanne is; 433 children or 13.1% of the population are between 0 and 9 years old and 464 teenagers or 14.1% are between 10 and 19. Of the adult population, 291 people or 8.8% of the population are between 20 and 29 years old. 444 people or 13.5% are between 30 and 39, 645 people or 19.6% are between 40 and 49, and 469 people or 14.2% are between 50 and 59. The senior population distribution is 336 people or 10.2% of the population are between 60 and 69 years old, 153 people or 4.6% are between 70 and 79, there are 51 people or 1.5% who are between 80 and 89, and there are 7 people or 0.2% who are 90 and older.