Burden Sharing Definition: Military Spending Explained (2025)
Burden sharing is the concept of dividing collective defense costs, measured against a 2025 world military expenditure total of $2,740.0bn across 149 countries.
Key takeaways
- Burden sharing measures a country's military spending as a share of a defined total — in 2025, the broadest such total is $2,740.0bn, our calculation from SIPRI country-level data across 149 countries.
- The $2,740.0bn figure is a floor, not the whole world: it covers only the 149 countries SIPRI reports for 2025, so some spenders (e.g., North Korea) are excluded.
- Burden sharing can also be expressed as share of GDP or per capita spending, not just share of world total.
- NATO and other alliance burden-sharing figures use a narrower denominator (combined alliance spending), not the full $2,740.0bn world total.
- Full country-by-country shares of the 2025 total are available on the 2025 world rankings page.
Verdict
Burden sharing is best understood as a share-of-total calculation: in 2025, the world total to measure it against is $2,740.0bn, our calculation from SIPRI country-level data across 149 countries. Because some spenders are missing from the dataset, this figure is a floor on true global military expenditure, not the complete total.
At a glance
| World military expenditure (2025) | $2,740.0bnFloor across 149 SIPRI-reported countries, not a literal global total |
|---|---|
| Countries included | 149SIPRI-reported series for 2025 |
| Currency basis | SIPRI constant 2024 USD |
| Figure type | Actual, not estimate2025 is not an estimate year |
| Coverage status | Floor, not totalSome spenders absent from SIPRI dataset |
Burden sharing is the idea that the cost of collective defense should be divided among allied or peer countries according to some agreed measure — most often each country's share of a total military expenditure figure. In 2025, the world total that any burden-sharing calculation is measured against is $2,740.0bn — a floor across the 149 countries SIPRI reports, not a literal global total — our calculation from SIPRI country-level data.
Source: SIPRI Military Expenditure Database. Data as of 2026-08-25.
01 What Does 'Burden Sharing' Mean in Defense Policy?
In defense policy, "burden sharing" describes how the costs of collective security — whether within an alliance like NATO, a coalition, or the abstract idea of "the world's defense burden" — are distributed across the countries involved. The term is used constantly in political debate, but it only becomes meaningful once it is tied to a number: a share of GDP, a share of an alliance budget, or a share of world military expenditure.
At its simplest, burden sharing is a ratio: one country's military spending divided by a relevant total. The denominator matters as much as the numerator. This entry uses the broadest possible denominator — the world total — as the baseline before narrower alliance-specific comparisons are layered on.
02 The World Total: The Denominator Burden Sharing Is Measured Against
For 2025, summing SIPRI's country-level military expenditure series across the 149 countries SIPRI reports produces a world total of $2,740.0bn, in SIPRI constant 2024 US dollars. This is not a figure SIPRI itself publishes as a headline total — it is our calculation from SIPRI's country data, built specifically so readers can see the denominator any burden-sharing share is measured against.
03 How Burden Sharing Is Calculated: Share of Total, Share of GDP, Per Capita
Burden sharing is typically expressed one of three ways, and each answers a different question:
- Share of world total — a country's spending divided by the $2,740.0bn 2025 world total. This answers "how much of the global military expenditure does this country account for?"
- Share of GDP — spending as a percentage of a country's own economic output, the metric NATO's 2% guideline uses. This answers "how much of its own economy does a country devote to defense?" and is independent of the world total.
- Per capita spending — total spending divided by population, used to compare burden at the level of the individual taxpayer rather than the national economy.
The world-total share is the broadest and most neutral of the three, because it does not require country-specific GDP or population data — only the $2,740.0bn denominator and a country's own reported spending. Full country-by-country shares for 2025 are available on the 2025 world rankings page.
04 Why the $2,740.0bn Figure Is a Floor, Not the Whole World
The $2,740.0bn total covers the 149 countries SIPRI has a reportable series for in 2025 — it is not literally every state on earth.
Sum of the 149 countries SIPRI reports for 2025. Some spenders are absent from the dataset (North Korea has no series; several states have gaps), so this is a floor, not the whole world. Any burden-sharing share calculated against $2,740.0bn is therefore a share of this reported total, not of true global spending.
This matters for burden sharing specifically: a country's share of $2,740.0bn will always run slightly higher than its true share of world spending would be if every state's expenditure were known, because the denominator is a floor. The gap is generally small for large economies but can be more significant when comparing against the true global picture.
05 Burden Sharing in Practice: NATO and Alliance Contexts
Most public burden-sharing debate happens inside alliances, especially NATO, where member states are compared against each other and against spending guidelines rather than against the world total. Those alliance-level comparisons use a narrower denominator — the combined spending of alliance members — rather than the $2,740.0bn world figure used here.
The world total in this entry is deliberately the broadest possible denominator. Alliance-specific burden-sharing figures (e.g., a country's share of NATO's combined spending) will differ from a share of the $2,740.0bn world total, since NATO members are a subset of the 149 countries included here.
Whichever denominator is used, the underlying logic of burden sharing stays the same: a country's spending, expressed as a share of a defined total, is the number that turns a political talking point into a citable figure. For the full 2025 country-by-country breakdown, see the 2025 world rankings, or browse related terms in the glossary.
Frequently Asked Questions
- What is the definition of burden sharing in defense spending?
- Burden sharing is the concept of dividing the cost of collective defense among countries, typically expressed as each country's share of a total — such as the $2,740.0bn 2025 world military expenditure total calculated from SIPRI's 149-country dataset.
- What is the world military expenditure total used to calculate burden sharing in 2025?
- $2,740.0bn, our calculation from SIPRI country-level data across the 149 countries SIPRI reports for 2025. This is not a total SIPRI itself publishes.
- Does the $2,740.0bn total include every country in the world?
- No. It covers only the 149 countries SIPRI reports for 2025. Some spenders, including North Korea, have no SIPRI series, and other states have gaps, making this a floor rather than the true global total.
- Is burden sharing the same as NATO's 2% of GDP guideline?
- No. NATO's 2%-of-GDP guideline is one specific burden-sharing metric measured against each member's own economy. Burden sharing more broadly can also be measured as a share of world total military expenditure or per capita spending.
defensebudget.org
Defense spending data, sourced from SIPRI
defensebudget.org tracks military expenditure for 160 countries using the SIPRI Military Expenditure Database. Pages are generated from that dataset and reviewed before publication.