Municipality Trzin, which is part of the Osrednjeslovenska statistical region, measures 9 km2; this ranks it 209th among Slovene municipalities.
Statistical data for 2011 reveal the following:
In the middle of 2011 about 3,850 people (about 1,900 men and 1,950 women) were living in the municipality, which ranks Trzin 133rd among Slovene municipalities. The population density was 447 people per square kilometre, which was higher than the national average of 101 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 2.1 (in Slovenia 1.6). The number of people who moved from the municipality was higher than the number of people who moved into the municipality, so net migration per 1,000 population in the municipality was negative. It was -6.5. The sum of natural increase and net migration per 1,000 population in the municipality was negative. It was -4.4 (in Slovenia 2.6).
The mean age of people in Trzin was 40.4 years, which was lower than the national average (41.8).
In contrast to most Slovene municipalities, in Trzin the number of young people was higher than the number of old people: there were 87 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 117. 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 Slovene municipalities higher than the ageing index for men. In Trzin – in contrast to most Slovene municipalities – the same number of women were 65+ years old as 14 or less; as regards men, fewer were 65+ years old than 14 or less.
Trzin had 2 kindergartens. They were attended by 257 children or 85% of all children aged 1–5, which was more than the national average of 76%. In the school year 2011/2012 basic school in Trzin was attended by about 390 pupils, while various upper secondary schools were attended by about 140 pupils. There were 50 students and 14 graduates per 1,000 people in the municipality; in Slovenia the averages were 51 per 1,000 and 10 per 1,000, respectively.
Among people aged 15–64 (i.e. working age population) about 62% were persons in employment (i.e. persons in paid employment or self-employed persons), which is more than the national average of 58%.
The registered unemployment rate was 8.1%, which is less than the national average (11.8%). In contrast to most Slovene municipalities, more men than women were unemployed.
In Trzin, average monthly gross earnings per person employed by legal persons were about 6% lower than the annual average of monthly earnings for Slovenia; and net earnings about 6% lower.
Every 57th person in the municipality was receiving at least one financial social assistance. In Slovenia as a whole every 24th person received at least one financial social assistance.
In 2011, there were 380 dwellings per 1,000 population. About 78% of dwellings had at least three rooms. Average size of dwellings in the municipality was 93 m2.
Every person in Trzin had a car (70 passenger cars per 100 population); cars in this municipality were on average 6 years old.
In 2011, 681 kg of municipal waste per person was collected in Trzin, which is 329 kg more than on average in Slovenia.