Municipality Šoštanj, which is part of the Savinjska statistical region, measures 96 km2; this ranks it 74th among Slovene municipalities.
Statistical data for 2019 reveal the following:
In the middle of 2019 about 8,740 people (about 4,460 men and 4,280 women) were living in the municipality, which ranks Šoštanj 60th among Slovene municipalities. The population density was 91 people per square kilometre, which was lower than the national average of 103 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 -2.5 (in Slovenia -0.6). 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 11.6. The sum of natural increase and net migration per 1,000 population in the municipality was positive. It was 9.0 (in Slovenia 7.2).
The mean age of people in Šoštanj was 43.3 years, which was lower than the national average (43.4).
As in most Slovene municipalities, in Šoštanj the number of old people was higher than the number of young people: there were 123 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 133. It also shows that the mean age of people in Šoštanj 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 two (Jezersko and Loški Potok) higher than the ageing index for men. In Šoštanj – as in most Slovene municipalities – more women were 65+ years old than 14 or less; for men the situation was exactly the opposite.
Šoštanj had 3 kindergartens. They were attended by 410 children or 84% of all children aged 1–5, which was more than the national average of 81%. In the school year 2019/20 elementary schools in Šoštanj were attended by about 790 pupils, while various upper secondary schools were attended by about 340 pupils. There were 36 students and 9 graduates per 1,000 people in the municipality; in Slovenia the averages were 37 per 1,000 and 8 per 1,000, respectively.
Among people aged 15–64 (i.e. working age population) about 66% were persons in employment (i.e. persons in paid employment or self-employed persons), which is the same as the national average.
In Šoštanj, average monthly gross earnings per person employed by legal persons were about 6% lower than the annual average of monthly earnings for Slovenia; net earnings were about 5% lower.
Among 100 inhabitants in the municipality, 54 had a passenger car. The car was on average 11 years old.
In 2019, 288 kg of municipal waste per person was collected in Šoštanj, which is 71 kg less than on average in Slovenia.