 Of the Swiss national languages (), 3,556 speak German, 4 people speak French, 33 people speak Italian,

The age distribution, , in Zuzwil is; 592 children or 15.6% of the population are between 0 and 9 years old and 574 teenagers or 15.1% are between 10 and 19.Of the adult population, 397 people or 10.5% of the population are between 20 and 29 years old.684 people or 18.0% are between 30 and 39, 623 people or 16.4% are between 40 and 49, and 487 people or 12.8% are between 50 and 59.