The age distribution, , in Herznach is; 160 children or 12.4% of the population are between 0 and 9 years old and 170 teenagers or 13.2% are between 10 and 19. Of the adult population, 167 people or 12.9% of the population are between 20 and 29 years old. 172 people or 13.3% are between 30 and 39, 211 people or 16.4% are between 40 and 49, and 201 people or 15.6% are between 50 and 59. The senior population distribution is 112 people or 8.7% of the population are between 60 and 69 years old, 56 people or 4.3% are between 70 and 79, there are 36 people or 2.8% who are between 80 and 89,and there are 5 people or 0.4% who are 90 and older.