The age distribution, , in Montagny is; 242 children or 13.7% of the population are between 0 and 9 years old and 224 teenagers or 12.7% are between 10 and 19. Of the adult population, 213 people or 12.1% of the population are between 20 and 29 years old. 296 people or 16.8% are between 30 and 39, 244 people or 13.8% are between 40 and 49, and 227 people or 12.9% are between 50 and 59. The senior population distribution is 132 people or 7.5% of the population are between 60 and 69 years old, 117 people or 6.6% are between 70 and 79, there are 58 people or 3.3% who are between 80 and 89, and there are 9 people or 0.5% who are 90 and older.