US military spending as a share of GDP
1816 to 2031, from three independent sources. Shaded bands are major wars. Hover the chart for values.
Since 1946: the long glide down
Insights
1. For 125 years, the US barely had a peacetime military budget
From 1816 to 1939, peacetime spending averaged well under 1% of GDP (0.7% before the Civil War, 0.5% from 1871 to 1913, 0.8% between the wars). Spending only jumped during wars and fell straight back after: 15.5% in the Civil War, 9.8% in WWI.
2. WWII was the largest mobilisation in US history
National defense went from 1.7% of GDP in 1940 to 37.0% in 1944, more than a third of the whole economy, in four years.
3. After 1945 it never went back
Unlike after every earlier war, spending stayed high: the Cold War averaged 7.5% of GDP (1950 to 1989). That is the birth of a permanent, large standing military.
4. Each new peak has been lower than the last
Korea 13.8% (1953), Vietnam 9.1% (1968), the 1980s buildup 6.0% (1986), Afghanistan and Iraq 4.7% (2010). The economy grew faster than the defense budget, so the share kept falling even when spending rose in dollars.
5. Today is close to the post Cold War low
At 3.0% of GDP (FY2022 to FY2025) the share is near its lowest since 1940: the floor was 2.9% in 1999 to 2001. The average since 1990 is 3.6%.
6. The budget plans a turn upward
The FY2027 budget estimates rise to 3.6% in FY2027 and 3.7% in FY2028, the first planned increase in the share since the Afghanistan and Iraq years. These are estimates, not actuals.
Note: share of GDP is not the same as dollars. A falling share can still mean a bigger budget in dollars, because GDP grows.
Data sources
OMB: White House Office of Management and Budget, Historical Tables, Table 3.1, "National defense" outlays as a percentage of GDP, fiscal years 1940 to 2031 (2026 onwards are estimates), from the FY2027 budget. whitehouse.gov/omb/budget/historical-tables
GMSD: Barnum et al., Global Military Spending Dataset, version 9 (2025), processed by Our World in Data, calendar years 1816 to 2019. A model that combines many historical sources. ourworldindata.org
SIPRI: Stockholm International Peace Research Institute military expenditure, published by the World Bank (indicator MS.MIL.XPND.GD.ZS), calendar years 1960 to 2025. data.worldbank.org
Why they differ: OMB counts the federal "national defense" budget function by fiscal year. SIPRI uses a broader standard definition (calendar year, for example including military pensions), so it runs a little higher. GMSD is a modelled estimate designed for long comparisons across countries, and runs lower. The direction and turning points agree across all three.
Download the data (CSV) · Built 13 November 2026.