Archiac is located in the south of the department of Charente-Maritime in the former province of Saintonge some 20 km south of Cognac and 15 km north-west of Saint-Hilaire. The village is located at the intersection of two main highways: the D699 from Arthenac in the south-west to Ambleville in the north-east; and the D731 from Cierzac in the north-west which continues south-east from the village. The north-eastern border of the commune is also the border between Charente-Maritime and Charente departments. Other access roads include the D149 which is a short-cut connection between the D699 and the D733 west of the village and the D152 which goes south from the village to Saint-Maigrin. There are also the hamlets of La Grue and Saint-Pierre north-east of the village. Apart from some wooded areas near the village the commune is entirely farmland.
In 2009 the commune had 812 inhabitants. The evolution of the number of inhabitants is known from the population censuses conducted in the commune since 1793. From the 21st century, a census of communes with fewer than 10,000 inhabitants is held every five years, unlike larger towns that have a sample survey every year.[Note 1]
The population of the town is relatively old. The ratio of persons above the age of 60 years (32.4%) is higher than the national average (21.6%) and the departmental average (28.1%). As for the national and departmental levels, the female population of the commune is higher than the male population. The ratio (53.2%) is higher than the national ratio (51.6%).
Percentage Distribution of Age Groups in Archiac and Charente-Maritime Department in 2009
^At the beginning of the 21st century, the methods of identification have been modified by Law No. 2002-276 of 27 February 2002, the so-called "law of local democracy" and in particular Title V "census operations" allows, after a transitional period running from 2004 to 2008, the annual publication of the legal population of the different French administrative districts. For communes with a population greater than 10,000 inhabitants, a sample survey is conducted annually, the entire territory of these communes is taken into account at the end of the period of five years. The first "legal population" after 1999 under this new law came into force in 1 January 2009 and was based on the census of 2006.