Municipality Mežica, which is part of the koroška statistical region, measures 26 km2; this ranks it 188th among Slovene municipalities.
Statistical data for 2016 reveal the following:
In the middle of 2016 about 3,570 people (about 1,810 men and 1,760 women) were living in the municipality, which ranks Mežica 137th among Slovene municipalities. The population density was 135 people per square kilometre, which was higher than the national average 102 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 1.1 (in Slovenia 0.3). 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 -8.7. The sum of natural increase and net migration per 1,000 population in the municipality was negative. It was -7.6 (in Slovenia 0.8).
The mean age of people in Mežica was 45.2 years, which was higher than the national average (42.9).
As in most Slovene municipalities, in Mežica the number of old people was higher than the number of young people: there were 156 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 125. It also shows that the mean age of people in Mežica is growing more rapidly 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 Mežica – As in most Slovene municipalities – more women were 65+ years old than 14 or less; for men the situation was the same.
In the school year 2016/2017 basic school in Mežica was attended by about 300 pupils, while various upper secondary schools were attended by about 120 pupils. There were 30 students and 13 graduates per 1,000 people in the municipality; in Slovenia the averages were 39 per 1,000 and 15 per 1,000, respectively.
Among people aged 15–64 (i.e. working age population) about 56% were persons in employment (i.e. persons in paid employment or self-employed persons), which is less than national average (60%).
The registered unemployment rate was 8.9%, which is less than the national average (11.2%). As in most Slovene municipalities, more women than men were unemployed.
In Mežica, average monthly gross earnings per person employed by legal persons were about 3% higher than the annual average of monthly earnings for Slovenia; and net earnings about 2% higher.
In 2015, there were 411 dwellings per 1,000 population. About 48% of dwellings had at least three rooms. Average size of dwellings in the municipality was 75 m2.
Every other person in Mežica had a car (50 passenger cars per 100 population); cars in this municipality were on average 10 years old.
In 2016, 264 kg of municipal waste per person was collected in Mežica, which is 83 kg less than on average in Slovenia.