Using the most updated data, we can see that in 2009 there is actually about a $544 billion difference between what GDP would have been had it continued to contract as rapidly as it did during the fourth quarter of 2008 and what it actually was. As Holtz-Eakin points out, the total amount of fiscal stimulus during that year was $260 billion. This suggests the Recovery Act produced about $2.10 in economy activity for every $1.00 in spending or tax cuts. That’s a pretty good multiplier.
And if we apply the same methodology to the entire lifespan of the Recovery Act, not just to 2009, the multiplier becomes even more impressive. The total cost of the stimulus bill was about $800 billion, delivered over the course of two years.
The difference between actual GDP through the first quarter of 2011 and what GDP would have been had it continued “falling off a cliff” is around $3.3 trillion—implying a multiplier of more than 4.