Municipality Postojna, which is part of the Notranjsko-kraška statistical region, measures 270 km2; this ranks it 13th among Slovene municipalities.
Statistical data for 2010 reveal the following:
In the middle of 2010 about 15,700 people (about 7,900 men and 7,800 women) were living in the municipality, which ranks Postojna 31st among Slovene municipalities. The population density was 58 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 1.5 (in Slovenia 1.8). The number of people who moved from the municipality was lower than the number of people who moved into the municipality, so net migration per 1,000 population in the municipality was positive. It was 3.4. The sum of natural increase and net migration per 1,000 population in the municipality was positive. It was 4.8 (in Slovenia 1.6).
The mean age of people in Postojna was 40.9 years, which was lower than the national average (41.6).
In contrast to most Slovene municipalities, in Postojna the number of old people was the same as the number of young people: there were 100 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 117. It also shows that the mean age of people in Postojna 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 Postojna – as in most Slovene municipalities – more women were 65+ years old than 14 or less; for men the situation was exactly the opposite.
Postojna had 4 kindergartens. They were attended by 616 children or 76% of all children aged 1–5, which was more than the national average of 74%. In the school year 2010/2011 elementary schools in Postojna were attended by about 1,200 pupils, while various upper secondary schools were attended by about 580 pupils. There were 49 students and 10 graduates per 1,000 people in the municipality; in Slovenia the averages were 52 per 1,000 and 10 per 1,000, respectively.
Among people aged 15–64 (i.e. working age population) about 63% were persons in employment (i.e. persons in paid employment or self-employed persons), which is more than the national average of 59%.
The registered unemployment rate was 8.6%, which is less than the national average (10.7%). As in most Slovene municipalities, more women than men were unemployed.
In Postojna, average monthly gross earnings per person employed by legal persons were about 6% lower than the annual average of monthly earnings for Slovenia; and net earnings about 5% lower.
Every 22nd person in the municipality was receiving at least one financial social assistance, which is the same as the national average.
The value of gross investment in new fixed assets in the municipality (EUR 1,334 per capita) was lower than the national average (EUR 2,176 per capita).
In 2010, there were 415 dwellings per 1,000 population. About 56% of dwellings had at least three rooms. Average size of dwellings in the municipality was 80 m2.
About every other person in Postojna had a car (53 passenger cars per 100 population); cars in this municipality were on average 8 years old.
In tourist accommodations in the municipality around 31,400 arrivals and 45,300 overnight stays of tourist were recorded, which is approximately 1.0 % of all arrivals and 0.5 % of all overnight stays of tourist in Slovenia.
In 2010, 404 kg of municipal waste per person was collected in Postojna, which is 15 kg more than on average in Slovenia.