Baby Diaper Size Guide: Sizes by Weight and When to Size Up

Diapers are sized by weight, not age, so the right size depends on how big your baby is today. A good fit keeps leaks and skin irritation away.

Typical weight ranges

Brands differ and ranges overlap. Always follow the weight range printed on the pack.

Signs the diaper is too small

• Leaks, especially up the back or out of the legs, even when the diaper is not full.
• Red marks around the thighs or waist.
• The tabs barely reach, or the diaper feels tight.
• Your baby is near the top of the weight range on the pack.

Signs the diaper is too big

• Gaps around the legs.
• The diaper sags at the back or the front.
• The waistband folds over or sits too low.

How many should I buy?

Newborns often need eight or more diapers a day, but they outgrow the smallest size quickly. Start with one pack of newborn and one pack of the next size, then top up once you see how fast your baby grows. Avoid buying large amounts of any one size in advance.

Fitting tips

• Fasten the tabs snugly but comfortably: you should be able to slide a finger under the waistband.
• Pull out the ruffles around the legs so they do not fold in.
• For newborns, fold the front down so the umbilical area stays uncovered.

This guide is general shopping advice, not medical advice. If your baby has a persistent rash, talk to your paediatrician.