Don't be concerned with average weight. Be concerned with is her weight appropriate/healthy for her height and build. It's all based on genetics. Some children are more lean than others. My two youngest (now 6) weighed around 30-35 lbs at that age. We are a lean/small build family. My friend's son who is 4 weighs closer to 45 lbs but is not fat. He comes from a taller stockier built family. If you are concerned with obesity, the best way to determine is to use her BMI or body mass index. But if I had to guess based on personal experience I would say between 30-40 lbs.