It includes birth weight, the body mass index of the parents, the number of people in the household, the mother's professional status and whether she smoked during pregnancy.
According to pediatrician Dr. Jonathan Fanaroff of Rainbow Babies & Children's Hospital, "that calculation would have an 80 percent chance of of being right to so it really does a good job. It is an important tool."
Breastfeeding is another practice that can help prevent obesity in children.
The researchers did their original study on 4,000 children from Finland. But they say the formula also proved accurate in studies in the United States and Italy.
Doctors say once children gain weight, it's difficult for them to lose it, so prevention from the earliest age is key.