From
Economic Research Report No. (ERR-103) 50 pp, October 2010 
USDA’s Economic Research Service uses the Food Assistance National Input-Output Multiplier (FANIOM) model to represent and measure linkages between USDA’s domestic food assistance programs and the U.S. economy. It also describes the assumptions and structure of the FANIOM model and illustrates its use by estimating the economic multiplier effect of the Supplemental Nutrition Assistance Program (SNAP), formerly known as food stamps.
The analysis of SNAP benefits as a fiscal stimulus finds that an increase of $1 billion in SNAP expenditures is estimated to increase economic activity by $1.79 billion. In other words, every $5 in new SNAP benefits generates as much as $9 of economic activity.