On 1 January 2022, Belgium’s population density was 377 inhabitants per km². However, this varies greatly from one place to another in the territory, between Daverdisse and its 25 inhabitants/km² and Saint-Josse-ten-Noode which has 23,234 inhabitants/km².

The Flemish Region registers a population density of 492 inhabitants/km², the Walloon Region 217 inhabitants/km² and the Brussels-Capital Region 7,528 inhabitants/km².

In Flanders, the five most densely populated municipalities can be found in the province of Antwerp with Mortsel (3,364 inhabitants/km²), Borsbeek (2,878 inhabitants/km²), Antwerp (2,597 inhabitants/km²), Edegem (2,568 inhabitants/km²) and Boom (2,551 inhabitants/km²). Conversely, four of the five least densely populated municipalities in Flanders can be found in West Flanders: Lo-Reninge (51 inhabitants/km²), Zuienkerke (55 inhabitants/km²), Alveringem (62 inhabitants/km²) and Heuvelland (84 inhabitants/km²), with Herstappe (59 inhabitants/km²), in the province of Limburg, coming in between in third place.

Saint-Nicolas (3,529 inhabitants/km²) is the smallest and most densely populated municipality in Wallonia. Liège (2,845 inhabitants/km²), Charleroi (1,966 inhabitants/km²), Seraing (1,814 inhabitants/km²) and Herstal (1,733 inhabitants/km²) complete the top five, almost exclusively from Liège. At the other end of the scale, the five least densely populated municipalities in Wallonia and Belgium are Daverdisse (25 inhabitants/km²), Vresse-sur-Semois (25 inhabitants/km²), Sainte-Ode (27 inhabitants/km²), La Roche-en-Ardenne (28 inhabitants/km²) and Herbeumont (29 inhabitants/km²). A ranking almost exclusively from Luxembourg, with the exception of Vresse-sur-Semois from Namur.

The most densely populated municipalities in the Brussels-Capital Region are Saint-Josse-ten-Noode (23,234 inhabitants/km²), Saint-Gilles (19,274 inhabitants/km²), Koekelberg (18,633 inhabitants/km²), Schaerbeek (16,540 inhabitants/km²) and Molenbeek-Saint-Jean (16,241 inhabitants/km²). The least densely populated are Watermael-Boitsfort (1,942 inhabitants/km²), Uccle (3,720 inhabitants/km²), Auderghem (3,902 inhabitants/km²), Woluwe-Saint-Pierre (4,720 inhabitants/km²) and Brussels (5,704 inhabitants/km²).

18 of the 19 Brussels municipalities are among the most densely populated in Belgium, with Saint-Nicolas and Mortsel being the only representatives of their respective regions in the top 20.