Municipality Žalec, which is part of the Savinjska statistical region, measures 117 km2; this ranks it 54th among Slovene municipalities.
Statistical data for 2021 reveal the following:
In the middle of 2021 about 21,490 people (about 10,840 men and 10,650 women) were living in the municipality, which ranks Žalec 17th among Slovene municipalities. The population density was 184 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 -2.9 (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 -0.4. The sum of natural increase and net migration per 1,000 population in the municipality was negative. It was -3.3 (in Slovenia -0.9).
The mean age of people in Žalec was 44.5 years, which was lower than the national average (43.8).
As in most Slovene municipalities, in Žalec the number of old people was higher than the number of young people: there were 146 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 139. It also shows that the mean age of people in Žalec 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 five (Črna na Koroškem, Dobrovnik/Dobronak, Jezersko, Loški Potok in Mislinja) higher than the ageing index for men. In Žalec – as in most Slovene municipalities – more women were 65+ years old than 14 or less; for men the situation was the same.
Žalec had 11 kindergartens, which were attended by 793 children. Of all children in the municipality aged 1–5, 80% were included in kindergartens, which was less than the national average of 81%. In the school year 2021/22 elementary schools in Žalec were attended by about 2,180 pupils, while various upper secondary schools were attended by about 790 pupils. There were 36 students and 8 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 67% were persons in employment (i.e. persons in paid employment or self-employed persons), which is the same as the national average.
In Žalec, average monthly gross earnings per person employed by legal persons were about 12% lower than the annual average of monthly earnings for Slovenia; net earnings were about 10% lower.
Among 1,000 inhabitants in the municipality, 582 had a passenger car. The car was on average 11 years old.
In 2021, 436 kg of municipal waste per person was collected in Žalec, which is 71 kg more than on average in Slovenia.