It is impossible for the U.S. National Debt clock to be completely accurate at any given moment in time. The U.S. Treasury updates its information on a daily basis and US Debt Clock.org utilizes this information with complex algorithms and exacting standards to create a sliding scale of those numbers.
There are many digital and physical iterations of the United States Debt Clock, but the most accurate debt clock is US Debt Clock.org. This website has an array of real-time sources for its information, including the U.S. Treasury, the U.S. Census and the Federal Reserve. It also draws information from the Congressional Budget Office, the Office of Management and Budget and the Internal Revenue Service.
The famous National Debt Clock on 44th Street and 6th Avenue in New York City, constructed by real estate developer Seymour Durst, runs on a algorithm similar to the one US Debt Clock.org uses. On Sept. 30, 2008, the National Debt Clock had to be remodeled for the addition of an extra digit when the national debt hit $10 trillion.
Many politicians feature a version of the U.S. National Debt Clock on their websites; these clocks have been criticized for their inaccuracies. At times, some of these debt clocks have shown discrepancies as large as $756 billion, or roughly 5 percent, states National Journal.