The two bars show two equivalent ways of calculating GDP. The height of each bar above the horizontal axis represents $16,803 billion, U.S. GDP in 2013. The left bar shows the breakdown of GDP according to the value added of each sector of the economy. The right bar shows the breakdown of GDP according to the four types of aggregate spending: C + I + G + X − IM. The right bar has a total length of $16,803 billion + $494 billion = $17,297 billion. The $494 billion, shown as the area extending below the horizontal axis, is the amount of total spending absorbed by net imports (negative net exports) in 2013.
Source: Bureau of Economic Analysis.