Municipality Zagorje ob Savi, which is part of the Zasavska statistical region, measures 147 km2; this ranks it 43rd among Slovene municipalities.
Statistical data for 2020 reveal the following:
In the middle of 2020 about 16,400 people (about 8,200 men and 8,200 women) were living in the municipality, which ranks Zagorje ob Savi 31st among Slovene municipalities. The population density was 111 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 -2.6 (in Slovenia -2.5). 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 -0.5. The sum of natural increase and net migration per 1,000 population in the municipality was negative. It was -3.0 (in Slovenia 6.2).
The mean age of people in Zagorje ob Savi was 44.1 years, which was higher than the national average (43.6).
As in most Slovene municipalities, in Zagorje ob Savi the number of old people was higher than the number of young people: there were 137 people, aged 65 or more, per 100 people aged 0–14. This ratio shows that the value of the ageing index was higher than the national average of 136. It also shows that the mean age of people in Zagorje ob Savi is growing more rapidly than in Slovenia as a whole. Data by sex show that the ageing index for women was in all municipalities except in three (Dobrovnik/Dobronak, Jezersko in Loški Potok) higher than the ageing index for men. In Zagorje ob Savi – as in most Slovene municipalities – more women were 65+ years old than 14 or less; for men the situation was the same.
Zagorje ob Savi had 5 kindergartens, which were attended by 646 children. Of all children in the municipality aged 1–5, 82% were included in kindergartens, which was more than national average of 81%. In the school year 2020/21 elementary schools in Zagorje ob Savi were attended by about 1,530 pupils, while various upper secondary schools were attended by about 590 pupils. There were 38 students and 8 graduates per 1,000 people in the municipality; in Slovenia the averages were 39 per 1,000 and 7 per 1,000, respectively.
Among people aged 15–64 (i.e. working age population) about 68% were persons in employment (i.e. persons in paid employment or self-employed persons), which is more than the national average (66%).
In Zagorje ob Savi, average monthly gross earnings per person employed by legal persons were about 13% lower than the annual average of monthly earnings for Slovenia; net earnings were about 12% lower.
Among 1,000 inhabitants in the municipality, 547 had a passenger car. The car was on average 10 years old.
In 2020, 337 kg of municipal waste per person was collected in Zagorje ob Savi, which is 18 kg less than on average in Slovenia.