The age distribution, , in Lüterswil-Gächliwil is; 28 children or 7.5% of the population are between 0 and 6 years old and 56 teenagers or 15.1% are between 7 and 19. Of the adult population, 16 people or 4.3% of the population are between 20 and 24 years old. 98 people or 26.4% are between 25 and 44, and 91 people or 24.5% are between 45 and 64. The senior population distribution is 48 people or 12.9% of the population are between 65 and 79 years old and there are 34 people or 9.2% who are over 80.