Amifontaine is located some 20 km south-east of Laon and 40 km north-west of Rheims. The Autoroute des Anglais (A25, E17) passes through the western side of the commune from north to south but has no exit in the commune. Access to the commune is by road D52 from Ramecourt in the north-west through the commune to the village and continuing south-east to Prouvais. There is also road D89 from La Malmaison in the north-east through the village to Juvincourt-et-Damary in the south-west. The D24 road also passes through the north of the commune from west to east forming the southern border of a large forested area extending beyond the northern border of the commune.
The commune is almost entirely farmland except for the forested area in the north.
La Source a l'Aisne rises north of the village and flows south-west joining La Miette stream and flowing to join the Aisne river near Pontavert.
In 2010, the commune had 418 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