http://useconomy.about.com/od/usdebtanddeficit/p/National-Debt-Under-Obama.htm
Year by Year Breakout:
•FY 2009 - Although this was actually President Bush's last budget, it was being implemented during Obama's first year. Congress agreed to add the first year's worth of spending from the Economic Stimulus Act to this. That $253 billion accrues to Obama.
•FY 2010 - Obama's first budget created a $1.293 trillion deficit.
•FY 2012 - The deficit was the largest in history, at $1.327 trillion.
•FY 2011 - It contributed $1.299 trillion to the debt.
•FY 2013 - This was the first Obama budget where the deficit, $901 billion, was less than $1 trillion.
On January 20, 2009, the day he was sworn in, the debt was $10.626 trillion. By January 20, 2013, it was $16.687 trillion -- a difference of $6 trillion.
However, it's a little misleading to hold Obama (or any other President) accountable for the deficit incurred during his first year of office. That's because
the budget for that fiscal year was already set by the previous President. Bush's last budget (FY 2009) created a deficit of $1.16 trillion, even without the spending on the Economic Stimulus Act. Most of this addition to the debt occurred after the new President took office, and so should not be attributed to Obama.