Baby Clothes Size Chart: Size by Age, Weight and Height

Baby clothes sizes follow your baby’s weight and length more than their age. On Carter’s chart, 3M fits 9 to 12.5 lb and 21.5 to 24 inches, and the same baby can wear a different size at Gerber Childrenswear. This guide gives both brands’ charts side by side. It belongs with our baby gear guide, which covers what a newborn actually needs. To get a size in seconds, use the baby size finder.

What size is my baby by age, weight and height?

The comparison table above lists seven sizes from newborn to 24 months for two brands. Carter’s labels each size with an approximate age: NB is newborn, 3M is 0 to 3 months, 6M is 3 to 6 months, 9M is 6 to 9 months, 12M is 9 to 12 months, 18M is 12 to 18 months and 24M is 18 to 24 months. Gerber Childrenswear’s labels, such as 0-3M and 3-6M, name an age span too.

Both brands set the range by weight and length, so use those two numbers first and the age label second.

How do brands differ?

The charts use similar steps but different edges. Carter’s NB covers 6 to 9 lb, while Gerber’s Newborn covers 5 to 8 lb. At 13 lb a baby is a Carter’s 6M but a Gerber 3-6M. Gerber also lists a 0-6M size, up to 16 lb, that overlaps its other sizes, and a separate pajama chart. Other brands have their own charts, so treat any one table as a guide.

How do I measure my baby?

Weigh your baby on digital baby scales, which Cambridge University Hospitals say are likely to give the most accurate reading, and measure length lying down. Their method uses two adults: lay the baby on a towel at a right angle to a wall with the head against the wall, gently straighten the legs, put a firm book at the base of the feet and read the tape measure at the heels. Do not force the legs straight. Your pediatrician’s office also records weight and length at check-ups.

When should I size up?

If weight and length point to two different sizes, the larger size is the safer choice for comfort, and the finder shows both. When a measurement sits exactly on a shared edge, such as 21.5 inches on Carter’s chart, the larger size also applies. Babies grow quickly, so check the chart again before you buy for a new season.

Sleepwear follows its own rules. Gerber says its cotton pajamas are designed to fit snug for a child’s safety and publishes a separate chart for them. Check the maker’s guidance for the exact pajama size, and read our safe sleep tips for the sleep space.

What size should I buy as a gift?

Pick the size your baby will wear when the gift is used, not the size for today, and check the brand’s chart for that range. Our list of safe gifts for newborns and infants covers products as well as clothes, and a gift receipt lets the parents swap a size that does not fit.

Can this chart tell me if my baby is growing well?

No. A clothing chart tells you which size of a brand’s garment matches a measurement. It is not a growth chart. Questions about your baby’s weight or length are for your pediatrician, who tracks growth at check-ups.