SNAP for Kids Act of 2018 This bill modifies the Supplemental Nutrition Assistance Program (SNAP, formerly known as the food stamp program) to (1) increase benefits for certain small households with children who are 5-17 years old, and (2) require benefits for the households to be calculated using the low-cost food plan. The "low-cost food plan" is the diet required to feed a family of 4, consisting of a man and a woman 19-50 years old, a child 6-8 years old, and a child 9-11 years old, at a cost that is in the second quartile of food expenditures for those families in the United States.