Antichan-de-Frontignes is located at the foot of the Pyrenees in the Comminges region some 40 km east by south-east of Bagnères-de-Bigorre and 19 km south by south-west of Saint-Gaudens. Access to the commune is by the D618 road which branches from the D331 east of Ore and goes to the village then continues north-east by a roundabout route to Juzet-d'Izaut. There is also a local road going from the D618 north of the village to Saint-Pé-d'Ardet. Most of the commune is heavily forested however there is some farmland near the village.
In 2010 the commune had 82 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 communes that have a sample survey every year.[Note 1]
^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.