When choosing a sponge size we recommend going for one which would sit comfortably in the palm of your hand this usually means a size 13 cm or above for use by teens and adults for use on babies and toddlers we advise going for the smaller sizes of 9 cm and 10 5 cm having said that there is no hard and fast rule and you may well wish to start out with a small size if youve never used a natural sea sponge before and are looking to get a feel of it first before settling on your ideal size la