Municipality Mirna, which is part of the Jugovzhodna Slovenija statistical region, measures 31 km2; this ranks it 174th among Slovene municipalities.
Statistical data for 2012 reveal the following:
In the middle of 2012 about 2,550 people (about 1,250 men and 1,300 women) were living in the municipality, which ranks Mirna 167th among Slovene municipalities. The population density was 82 people per square kilometre, which was lower than the national average of 101 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 0.4 (in Slovenia 1.3). 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 -12. The sum of natural increase and net migration per 1,000 population in the municipality was negative. It was -11.7 (in Slovenia 1.6).
The mean age of people in Mirna was 40.8 years, which was lower than the national average (42).
As in most Slovene municipalities, in Mirna the number of old people was higher than the number of young people: there were 103 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 118. It also shows that the mean age of people in Mirna is growing more slowly 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 Mirna – as in most Slovene municipalities – more women were 65+ years old than 14 or less; for men the situation was exactly the opposite.
Mirna had 1 kindergarten. They were attended by 109 children or 71% of all children aged 1–5, which was less than the national average of 75%. In the school year 2012/2013 basic school in Mirna was attended by about 220 pupils, while various upper secondary schools were attended by about 70 pupils. There were 60 students and 14 graduates per 1,000 people in the municipality; in Slovenia the averages were 47 per 1,000 and 10 per 1,000, respectively.
Among people aged 15–64 (i.e. working age population) about 60% were persons in employment (i.e. persons in paid employment or self-employed persons), which is more than the national average of 57%.
The registered unemployment rate was 10.7%, which is less than the national average (12%). As in most Slovene municipalities, more women than men were unemployed.
In Mirna, average monthly gross earnings per person employed by legal persons were about 11% lower than the annual average of monthly earnings for Slovenia; and net earnings about 8% lower.
In 2012, there were 458 dwellings per 1,000 population. About 48% of dwellings had at least three rooms. Average size of dwellings in the municipality was 74 m2.
Every third person in Mirna had a car (34 passenger cars per 100 population); cars in this municipality were on average 9 years old.
In 2012, 210 kg of municipal waste per person was collected in Mirna, which is 117 kg less than on average in Slovenia.