Municipality Trzin, which is part of the Osrednjeslovenska statistical region, measures 9 km2; this ranks it 210th among Slovene municipalities.
Statistical data for 2022 reveal the following:
In the middle of 2022 about 3,920 people (about 1,960 men and 1,960 women) were living in the municipality, which ranks Trzin 129th among Slovene municipalities. The population density was 455 people per square kilometre, which was higher than the national average of 104 people per square kilometre.
The number of live births was lower than the number of deaths, which means that natural increase per 1,000 population in the municipality was negative. It was –5.1 (in Slovenia –2.3). 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 19.4. The sum of natural increase and net migration per 1,000 population in the municipality was positive. It was 14.3 (in Slovenia 4.6).
The mean age of people in Trzin was 43.8 years, which was lower than the national average (43.9).
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 the same as the national average of 142. It also shows that the mean age of people in Trzin is growing as fast as in Slovenia as a whole. Data by sex show that the ageing index for women was in all municipalities except in four (Črna na Koroškem, Dobrovnik/Dobronak, 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 228 children. Of all children in the municipality aged 1–5, 88% were included in kindergartens, which was more than the national average of 82%. In the school year 2022/23 elementary school in Trzin was attended by about 460 pupils, while various upper secondary schools were attended by about 160 pupils. There were 49 students and 8 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 74% 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 earnings per person employed by legal persons were about 4% higher than the annual average of monthly earnings for Slovenia; net earnings were about 4% higher.
Among 1,000 inhabitants in the municipality, 756 had a passenger car. The car was on average 9 years old.
In 2022, 799 kg of municipal waste per person was collected in Trzin, which is 438 kg more than on average in Slovenia.