Some resources that provide information regarding the protein content of common foods are the National Nutrient Database for Standard Reference and Today's Dietitian. These websites provide information about the protein contents of meat, seafood, dairy, vegetables and many other types of foods.
The National Nutrient Database for Standard Reference is a resource produced by the U.S. Department of Agriculture that allows users to search for the exact protein content in grams of all possible food groups.
Another resource that can determine the protein content of common foods is Today's Dietition, which provides the serving size, calories and protein content of common foods that are protein-rich. Today's Dietitian allows individuals who diet to maximize the protein in their diets and minimize the number of calories consumed.