The U.S. national debt has reached $40 trillion and now exceeds 123% of GDP. Federal liabilities therefore stand larger than annual economic output, with the debt-to-GDP ratio (government debt relative to economic size) above 123%. The $40 trillion mark is a round-number milestone in the absolute stock of national debt, while the 123% reading shows how far that stock has grown relative to GDP. High debt-to-GDP levels can increase the cost of servicing government borrowing and shape market views of long-term fiscal sustainability.