| Country | Military service age and obligation |
| Afghanistan | 22 years of age; inductees are contracted into service for a 4-year term (2005) |
| Akrotiri | void |
| Albania | 19 years of age (2004) |
| Algeria | 19-30 years of age for compulsory military service; conscript service obligation - 18 months (6 months basic training, 12 months civil projects) (2006) |
| American Samoa | void |
| Andorra | void |
| Angola | 22-24 years of age for compulsory military service; conscript service obligation - 2 years; Angolan citizenship required (2009) |
| Anguilla | void |
| Antarctica | void |
| Antigua and Barbuda | 18 years of age for voluntary military service; no conscription (2008) |
| Arctic Ocean | void |
| Argentina | 18-24 years of age for voluntary military service (18-21 requires parental permission); no conscription (2001) |
| Armenia | 18-27 years of age for voluntary or compulsory military service; 2-year conscript service obligation (2007) |
| Aruba | void |
| Ashmore and Cartier Islands | void |
| Atlantic Ocean | void |
| Australia | 17 years of age for voluntary military service (with parental consent); no conscription; women allowed to serve in Army combat units in non-combat support roles (2008) |
| Austria | 18-35 years of age for compulsory military service; 16 years of age for male or female voluntary service; service obligation 6 months of training, followed by an 8-year reserve obligation; conscripts cannot be deployed in military operations outside Austria (2009) |
| Azerbaijan | men between 18 and 35 are liable for military service; 18 years of age for voluntary military service; length of military service is 18 months and 12 months for university graduates (2006) |
| Bahamas, The | 18 years of age (est.); no conscription (2008) |