Erquelinnes has 10,003 residents within 44.5 km², with an average age of about 40. Home ownership stands at 69%, and average net income is €15,160 per person per year. The population is 51.3% women. Nationalities are 92.9% Belgian, 4.9% French, 0.8% Italian, 0.1% Moroccan, 0.1% Lebanese, 0.1% Romanian, 0.1% Pakistani and 0.9% other. Houses account for 97% of dwellings, while 3% are in apartment buildings. The average dwelling has 6 rooms and the buildings date to around 1912 on average. Across the building stock, 33% are semi-closed houses, 29.3% closed houses, 27.8% open houses, farms and castles, 3.9% commercial houses, 3.2% other building types and 2.7% buildings and flat blocks.
There are currently 0 houses for rent in Erquelinnes. The stated average monthly rent is €0, and both the highest and lowest house-rental prices are €0. For local travel, the N40, N54a, N55 and D336 are among the roads serving the municipality. The A7 / E19–E42 motorway entrance is 24 minutes by car from the town centre; the A15 / E42 entrance is 27 minutes away. Bus routes include TEC 108 from Binche to Erquelinnes, TEC 129 from Macquenoise to Mons, TEC 134/ from Mons to Beaumont and express line E110 from Beaumont to Mons. The NMBS/SNCB Tournai–Mouscron bus line is also listed. Stations close to the centre include Erquelinnes-Village, Erquelinnes, Erquelinnes-Frontière, Solre-Sur-Sambre and Labuissière.
Families have access to 6 nurseries, 11 nursery schools, 11 primary schools and 2 secondary schools. Named examples include Ecole Fondamentale Libre Notre-Dame, Ecole Fondamentale Communale, Ecole D'Arts Et Metiers and Institut Technique De La Communaute Francaise Erquelinnes. Shops include 1 Trafic, 1 Colruyt and 1 Delhaize. There are no shared bicycles or shared cars in the municipality, and no known EV charging station. Brussels South Charleroi Airport is 33 minutes away by car and 52 minutes by public transport. The local housing stock averages 6 rooms per dwelling, and houses form the largest share of dwellings at 97%, alongside 3% in apartment buildings.