We hope these detailed size charts are helpful in determining the best fit. A helpful tip is to compare one of your favourite garments to our flat lay measurements in the below charts. For our sunsuits, if your baby is growing fast or if in doubt, we recommend sizing up for more longevity. Our polyester spandex fabric blend is very stretchy to provide some extra space for growth. If you have additional sizing questions, please don't hesitate to contact us!