The age distribution, , in Illgau is; 242 people or 33.6% of the population is between 0 and 19. 241 people or 33.4% are 20 to 39, and 166 people or 23.0% are 40 to 64.
The age distribution in Illgau reveals that 33.6% of the population is under 20 years old, 33.4% are between 20 and 39 years old, and 23.0% are between 40 and 64 years old.