Head-to-head comparison
US Debt-to-GDP vs Interest Expense
US debt-to-GDP vs interest expense — which matters more for fiscal sustainability?
Verdict
Interest Expense wins
Interest expense is the current-year fiscal constraint; debt-to-GDP is context for it.
One-year comparison
Left axis: debt-to-gdp-ratio (green) · Right axis: Interest Expense (blue)
The analysis
Debt-to-GDP measures the stock; interest expense measures the flow cost. A high debt level at low rates is manageable; a moderate debt level at high rates is not. Interest expense crossed $1T annualized in 2024, now exceeding defense spending. The interaction between high rates and high debt-to-GDP is what makes the post-pandemic fiscal trajectory structurally different from 2019.
Indicator A
debt-to-gdp-ratio
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Indicator B
Interest Expense
Track U.S. government interest payments on national debt. Rising interest expense crowds out fiscal stimulus capacity during downturns.
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