Municipality Trzin, which is part of the Osrednjeslovenska statistical region, measures 9 km2; this ranks it 210th among Slovene municipalities.
Statistical data for 2023 reveal the following:
In the middle of 2023 about 4,020 people (about 2,000 men and 2,020 women) were living in the municipality, which ranks Trzin 126th among Slovene municipalities. The population density was 466 people per square kilometre, which was higher than the national average of 105 people per square kilometre.
The number of live births was higher than the number of deaths, which means that natural increase per 1,000 population in the municipality was positive. It was 0.7 (in Slovenia –2.1). The number of people who moved from the municipality was lower than the number of people who moved into the municipality, so net migration per 1,000 population in the municipality was positive. It was 28.1. The sum of natural increase and net migration per 1,000 population in the municipality was positive. It was 28.9 (in Slovenia 3.3).
The mean age of people in Trzin was 44.0 years, which was lower than the national average (44.1).
As in most Slovene municipalities, in Trzin the number of old people was higher than the number of young people: there were 142 people, aged 65 or more, per 100 people aged 0–14. This ratio shows that the value of the ageing index was lower than the national average of 145. It also shows that the mean age of people in Trzin is growing more slowly than in Slovenia as a whole. Data by sex show that the ageing index for women was in all municipalities except in six (Črna na Koroškem, Dobrovnik/Dobronak, Grad, Hodoš/Hodos, Jezersko in Mislinja) higher than the ageing index for men. In Trzin – as in most Slovene municipalities – more women were 65+ years old than 14 or less; for men the situation was the same.
Trzin had 2 kindergartens, which were attended by 203 children. Of all children in the municipality aged 1–5, 85% were included in kindergartens, which was more than the national average of 83%. In the school year 2023/24 elementary school in Trzin was attended by about 460 pupils, while various upper secondary schools were attended by about 170 pupils. There were 50 students and 10 graduates per 1,000 people in the municipality; in Slovenia the averages were 38 per 1,000 and 8 per 1,000, respectively.
Among people aged 15–64 (i.e. working age population) about 75% were persons in employment (i.e. persons in paid employment or self–employed persons), which is more than the national average (69%).
In Trzin, average monthly gross and net earnings per person employed by legal persons were the same as the national average the annual average of monthly earnings for Slovenia.
Among 1,000 inhabitants in the municipality, 737 had a passenger car. The car was on average 9 years old.
In 2023, 709 kg of municipal waste per person was collected in Trzin, which is 331 kg more than on average in Slovenia.