While developmental growth is going full speed ahead, physical growth slows down during this year. After her first birthday, your toddler won't put weight on steadily. He/ she may gain only 3-4kgs this year. An average 15-month-old girl weighs about 22 pounds (10kgs) and stands 31 inches tall. Boys tend to be about a pound heavier at 15 months but about the same height. By age 2, both will stand about 34 inches tall and weigh about 27 or 28 pounds (12-13 kgs) on an average. Your toddler's head size will also more or less remain steady. He'll probably add about an inch to his head circumference, bringing him closer to his adult head size. Height depends on many factors including genetics. You should not worry too much, if your baby is growing well, is active and healthy.You should consult your pediatrician about this if you are concerned and he may able to chart your baby's Progress in height and weight regularly.