What is the average weight for a three month old girl?

At 3 months, the "typical" baby weighs 13 pounds and measures 24 inches. But don't worry if your baby is smaller or larger. Babies, like adults, vary in size and shape. In fact, the "average" weight for a 3-month-old can range from 9 to 16 pounds and the "average" length from 22 to 25 inches.