Children's sizes are ages, but children are not averages. Two minutes with a tape measure saves a return.
The three numbers
Height matters most. Stand them against a door frame, heels to the wood, and mark the top of the head with a pencil. Then measure the chest, under the arms, and the waist at the tummy button.
The biscuit method
Ask them to hold a biscuit in each hand with arms out like an aeroplane. You get about fifteen seconds of stillness, which is enough for a chest measurement.
If they are between two sizes, choose the larger one. Cuffs roll up. Sleeves do not grow.
Babies
For babies, measure length lying down, from the top of the head to the heel, and go by weight if you are unsure. Our popper suits are cut with room for a nappy.
Shoes
Stand them on a sheet of paper in the evening, when feet are at their largest, and mark heel and longest toe. Add one centimetre of growing room and compare it with the chart on the product page.