Municipality Šentjernej, which is part of the Jugovzhodna Slovenija statistical region, measures 96 km2; this ranks it 73rd among Slovene municipalities.
Statistical data for 2021 reveal the following:
In the middle of 2021 about 7,220 people (about 3,660 men and 3,570 women) were living in the municipality, which ranks Šentjernej 75th among Slovene municipalities. The population density was 75 people per square kilometre, which was lower than the national average of 104 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 5.5 (in Slovenia -2.0). 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 -1.9. The sum of natural increase and net migration per 1,000 population in the municipality was positive. It was 3.6 (in Slovenia -0.9).
The mean age of people in Šentjernej was 41.4 years, which was lower than the national average (43.8).
In contrast to most Slovene municipalities, in Šentjernej the number of young people was higher than the number of old people: there were 96 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 139. It also shows that the mean age of people in Šentjernej 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 five (Črna na Koroškem, Dobrovnik/Dobronak, Jezersko, Loški Potok in Mislinja) higher than the ageing index for men. In Šentjernej – as in most Slovene municipalities – more women were 65+ years old than 14 or less; for men the situation was exactly the opposite.
Šentjernej had 2 kindergartens, which were attended by 388 children. Of all children in the municipality aged 1–5, 79% were included in kindergartens, which was less than the national average of 81%. In the school year 2021/22 elementary schools in Šentjernej were attended by about 780 pupils, while various upper secondary schools were attended by about 260 pupils. There were 41 students and 7 graduates per 1,000 people in the municipality; in Slovenia the averages were 39 per 1,000 and 8 per 1,000, respectively.
Among people aged 15–64 (i.e. working age population) about 71% were persons in employment (i.e. persons in paid employment or self-employed persons), which is more than the national average (67%).
In Šentjernej, average monthly gross earnings per person employed by legal persons were the same as the national average the annual average of monthly earnings for Slovenia; net earnings were about 1% higher.
Among 1,000 inhabitants in the municipality, 599 had a passenger car. The car was on average 11 years old.
In 2021, 311 kg of municipal waste per person was collected in Šentjernej, which is 54 kg less than on average in Slovenia.