Aix is located some 50 km south-west of Clermont-Ferrand. The south eastern section of the commune is traversed by the TransEuroppienne Motorway (E70 / A89). Exit No. 24 is just next to the border and this exit to the north connects the motorway to the Highway D1089 which runs fairly parallel to the motorway from Ussel in the south-west to Merlines in the north-east passing through the heart of the commune. To reach the village of Aix it is possible to take the D40E2 which branches from the D1089 south-west of the commune and goes directly to the town. The town can also be accessed from the west on the D49 from Saint-Pardoux-le-Vieux which, after passing through the town, continues east to link with the D1089. There is also Highway D91 from the north as well as many small country roads.
To the south-east of the town about 1.5 km in a direct line is the railway station of La Marsalouse which is served by TER Limousin and TER Auvergne trains which link Clermont-Ferrand to Gare de Limoges-Bénédictins and Gare de Brive-la-Gaillarde. TER buses also connect Aix and La Marsalouse to Ussel and Montlucon town, this route having been transferred to the road on 29 February 2008.
There are many forests covering the commune with approximately 50% forest and 50% farmland.
The commune is covered by numerous streams including the Dozanne, the Sarsonne, the Dognon, the Jaloustre, and many others. Most of these flow into the Chavanon river which forms the border between the Correze and Puy-de-Dome departments in the south-east.
In 2009, the commune had 386 inhabitants. The evolution of the number of inhabitants is known through the population censuses conducted in the town since 1793. From the 21st century, a census of municipalities with fewer than 10,000 inhabitants is held every five years, unlike larger towns that have a sample survey every year.[Note 1][Note 2]
^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" which allow, after a transitional period running from 2004 to 2008, the annual publication of the legal population of the different French administrative districts. For municipalities with a population greater than 10,000 inhabitants, a sample survey is conducted annually, the entire territory of these municipalities 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.
^In the census table and the graph, by convention in Wikipedia, and to allow a fair comparison between five yearly censuses, the principle has been retained for subsequent legal populations since 1999 displayed in the census table and the graph that shows populations for the years 2006, 2011, 2016, etc.. , as well as the latest legal population published by INSEE