Castres Population and Area (Tarn)
Largest city in France 2026: up-to-date figures for Castres (Tarn)
Castres: Population and Area
With 43,800 inhabitants (INSEE total population in force on January 1, 2026), Castres is the 176th most populous town in France in 2026 and the 2nd most populous in the Tarn department, out of 314 communes. It covers 98 km² (241st largest area in France, 3rd largest in the department), with a population density of 446 inhabitants per km², or 4.1 times the national average (110 inhabitants/km²), which ranks it 2,056th in France for density.
Castres is located in the Tarn department (81), in the Occitanie region (formerly Midi-Pyrénées), where it ranks 13th by population out of 4,446 communes. The most populous town in the Tarn department is Albi (52,783 inhabitants); the department is home to 407,233 people over 5,758 km².
See the full ranking of communes in the Tarn department and the regional ranking: largest city in Occitanie.
Towns of similar size in the Tarn department: Albi (pop. 52,783), Gaillac (pop. 16,531), Graulhet (pop. 13,332), Lavaur (pop. 11,290).
Sources: INSEE, official population figures in force on January 1, 2026 (total population); areas: IGN / Observatoire des territoires; INSEE code 81065. Rankings are calculated across the 34,858 communes of metropolitan and overseas France in our database.