National Debt — Levels and Composition
Global government debt reached $97 trillion in 2024 — roughly 93% of world GDP. The US ($35.5T), Japan ($10T) and China ($14T) are the three largest stocks. But the same dollar of debt is far more burdensome in some countries than others. Maturity profile, currency composition, and creditor base shape sustainability more than headline numbers.
Key insights
Debt-to-GDP overstates uniformity
Japan runs gross debt of 237% of GDP without distress because: (1) most is owned domestically, (2) yields are very low, (3) the BoJ holds half. Argentina at 90% has been in serial default for decades because of foreign-currency exposure and short maturities. The same headline ratio implies very different things in different contexts.
Maturity profile matters more than level
A country with $10T of 30-year fixed-rate debt is insulated from rate shocks; a country with $1T of 1-year debt is exposed every refinancing window. The UK's average maturity is ~15 years (one of the longest); the US is ~5.5 years (one of the shortest among AAAs). Short maturity profile amplifies the budget impact of rising rates — US net interest costs have tripled since 2020 partly because of fast pass-through.
Domestic currency debt is far safer
Countries that borrow in their own currency can always service the debt by printing money (with inflation as the cost). Countries that borrow in foreign currency face hard default risk. 'Original sin' — emerging-market inability to borrow long-term in domestic currency — is being addressed slowly; the local-currency bond markets of India, Brazil, Mexico, Turkey have deepened substantially over 20 years.
Government debt / GDP — selected countries (2024)
Gross general government debt as % of GDP
Key Finding: Japan tops at 237%; emerging markets sit lower but face higher real rates; the US is the most-indebted AAA.
Government debt — top countries (USD trillions, 2024)
Total gross general government debt
Key Finding: US debt is more than twice Japan's, but Japan's debt-to-GDP is nearly double the US.
Methodology & caveats
Gross vs net debt
Gross debt counts all financial liabilities. Net debt subtracts government financial assets (cash, deposits, investments). For most countries gross-net difference is 10-20pp of GDP; for Norway with its sovereign wealth fund, net debt is negative. Comparisons should specify which is used.
Public vs publicly held
US federal debt has two components: 'debt held by the public' (~$28T) and 'intragovernmental holdings' (~$7T, mostly Social Security trust funds). Gross debt sums both; debt-held-by-public is the more economically meaningful figure. Different sources use different conventions.
Why ratings can lag fundamentals
Credit ratings (S&P, Moody's, Fitch) move slowly. The US has been on negative watch repeatedly without losing AAA at all three agencies (Fitch downgraded 2023). EM downgrades often come after market signals already shifted. Markets typically price risk earlier than ratings; spread movements lead rating actions by months to years.