This article is a list of countries by military expenditure, the amount spent by a nation on its military in a given year. Military expenditure figures are presented in US$ based on either constant or current exchange rates.^[1] These results can vary greatly from one year to another based on fluctuations in the exchange rates of each country's currency. Such fluctuations may change a country's ranking from one year to the next.

The first list is based on the 2015 edition of "The Military Balance" published by the International Institute for Strategic Studies(IISS) using average market exchange rates.^[2] The second list is based on the Stockholm International Peace Research Institute(SIPRI) 2015 Fact Sheet which includes a list on the world's top 15 military spenders in 2014, based on current market exchange rates.