According to the Food CPI and Expenditures table at the United Sates Department of Agriculture's web site, per capita spending on food in the U.S. in 2008 was $3,832. Of this total, $1,973 was spent on food prepared at home and $1,859 was spent on food prepared away from home. If you multiply $3,832 X 4, then a family of four would be expected to spend $15,382 per year on food, including both grocery store and restaurant expenditures. Food prepared at home only would be $7,892. ( Of course, this cost would vary from family to family depending on factors like the regional prices of food in your particular geographic area and the ages of your family members.) Visit my main site for tips on how to reduce your grocery bill.In a separate study from the U.S. government's Consumer Expenditure Survey, the average "consumer unit" of four spent $9,478 on food in 2008. Of this amount, $5,478 was spent on food at home and $4,000 was spent on food away from home.
Just for grins, the average of the two study results for a "consumer unit" of four comes out to $12,430, for the total amount spent on food, both home and away. If we only consider food prepared at home (what most normal people would simply call groceries), then that amount averages out to $6,685.
According to an article at MSNBC, "The Bureau of Labor Statistics estimates about 12.5 percent of the average family's spending goes toward food, while the Department of Agriculture puts the figure at 9.8 percent."
How much do you spend on groceries?

We try to spend under $500 a month for a family of three for both groceries and restaurant food but we don't always track it very closely so it could be more or less that amount.
My family of five eats well for about $300/month. I wrote Strategic Eating, The Econovore's Essential Guide, to share how to do it, because I think most family's food bill is the spending category where the most money can be saved.
we spend £40 a week, £160 a month and that is for all expenses including hair colour, cat/dog food/ all food and cleaning expenses and we live well