This is a list of countries by military expenditures. The first list is based on the Stockholm International Peace Research Institute (SIPRI) database which calculates military expenditures in 2009 (in constant 2008 US$). It also includes military expenditures as a percentage of gross domestic product (GDP) in 2008. The second list is based on the SIPRI Yearbook 2010 which includes a list on the world's top 15 military spenders in 2009 at current exchange rates.