Children's hat question

I’ve been making some adult hats with 10.5 needles in the round. I’d like to make a smaller child one. I have no kids and this is for a 4 year old. Can I just reduce the stiches from 60 to 40?

According to yarnstandards, the average toddler head circumference is 16", and child’s is 18". So if 40 stitches at your gauge puts you in that neighborhood, you shoudl be fine.