Just how big is our deficit?

The official number for US Federal debt is around $16 Trillion dollars, which is around 100% of GDP.  That's getting up there.  The highest previous number was around 120% at the very end of World War II.  This is the official value of bonds owed by the U.S. Government.

However, Niall Ferguson argues that these bond debts do not reflect the unfunded liabilities of promises made to support future entitlements such as Social Security and Medicare.  According to this article, the net present value (NPV) of these federal liabilities is $200 Trillion.  (States are on the hook for $38 Trillion)  Attempting to verify these figures, a Google search finds other values for federal liability of:

• $45 trillion, 
• $73 trillion ( in this excellent long PDF from BusinessWeek 2010), 
• $128 trillion (Seeking Alpha, the article says "8x official debt").  
• $75 trillion (Bill Gross, PIMCO manager)
• $120 trillion  (CATO institute, libertarian/conservative think tank)
• $100 trillion (Christian Science Monitor quoting Bill Gross)
• "over $60 trillion" (in 2010)
• $61.6 trillion (USA Today)
• $39 trillion for Medicare alone, and that is "substantially understated"
• $110 trillion

Now, many (but not all) of these are from more conservative sites who would be prone to overestimate the problem.  Nor do they give details of where the numbers came from.  But, taking a middle ground, it looks like the federal unfunded liability is very roughly $100 trillion.  This does not include states and municipalities.  Like Stockton CA, which is going bankrupt.  

One way to look at this problem is that, with a GDP of $16 trillion, it would take over six years of all of our GDP to "fund" this liability.  Another way is to figure cost per person.  There are about 313 million residents in the USA.  To pay for the federal unfunded liabilities, that would be $319,488 each.  Now the average net worth for an entire household (not an individual) is $77,000.  The average household is, very roughly, 2.5.  So, the average net worth for each US resident is about $30,000.  So the entire net worth of all residents in the USA is less than 10% of the federal liability.

Even if you take a low estimate of the liability (USA Today's $61 trillion), that is still about $200,000 per person.  A lot.  It's very clear that Congress must make serious, serious cuts to entitlements, such as future Medicare and Social Security benefits.