Municipality Semič, which is part of the Jugovzhodna Slovenija statistical region, measures 147 km2; this ranks it 42th among Slovene municipalities.
Statistical data for 2012 reveal the following:
In the middle of 2012 about 3,850 people (about 1,950 men and 1,900 women) were living in the municipality, which ranks Semič 132th among Slovene municipalities. The population density was 26 people per square kilometre, which was lower 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 3.4 (in Slovenia 1.3). 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 -15.1. The sum of natural increase and net migration per 1,000 population in the municipality was negative. It was -11.7 (in Slovenia 1.6).
The mean age of people in Semič was 42.0 years, which was the same as the national average.
As in most Slovene municipalities, in Semič the number of old people was higher than the number of young people: there were 109 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 118. It also shows that the mean age of people in Semič 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 Semič – as in most Slovene municipalities – more women were 65+ years old than 14 or less; for men the situation was exactly the opposite.
Semič had 1 kindergarten. They were attended by 139 children or 68% of all children aged 1–5, which was less than the national average of 75%. In the school year 2012/2013 basic schools in Semič were attended by about 300 pupils, while various upper secondary schools were attended by about 140 pupils. There were 50 students and 8 graduates per 1,000 people in the municipality; in Slovenia the averages were 47 per 1,000 and 10 per 1,000, respectively.
Among people aged 15–64 (i.e. working age population) about 60% were persons in employment (i.e. persons in paid employment or self-employed persons), which is more than the national average of 57%.
The registered unemployment rate was 15.5%, which is more than the national average (12%). As in most Slovene municipalities, more women than men were unemployed.
In Semič, average monthly gross earnings per person employed by legal persons were about 21% lower than the annual average of monthly earnings for Slovenia; and net earnings about 17% lower.
In 2012, there were 466 dwellings per 1,000 population. About 61% of dwellings had at least three rooms. Average size of dwellings in the municipality was 80 m2.
Every other person in Semič had a car (51 passenger cars per 100 population); cars in this municipality were on average 10 years old.
In 2012, 260 kg of municipal waste per person was collected in Semič, which is 67 kg less than on average in Slovenia.