Choosing the right size diapers for your baby: buying guide

From birth to about 2/3 years old, your baby will need diapers. It is also during this period that your baby will grow and his diaper size will change. Indeed, as your baby grows, it is essential to change diaper sizes as well so that they remain adapted to his morphology and so that there are no leaks. What size should you choose for your baby? How do you know if you should go to the next size? We answer all your questions in this article.

How do I choose a diaper size for my baby?

Here is a guide to help you choose your diaper size:




Diaper size 1

From 2 to 5 kg

For newborns, up to about 2 or 3 months

Diaper size 2

From 3 to 6 kg

For newborns up to about 3 months

Diaper size 3

From 4 to 9 kg

From 3 months to 6 months

Diaper size 4

From 7 to 18 kg

From 6 months to 10 months

Diaper size 4+

From 9 to 20 kg

From 10 months to 18 months

Diaper size 5

From 11 to 25 kg

For babies over 18 months

Diaper size 6

After 2/3 years, when your baby is potty trained, we recommend training pants

For premature babies or smaller sizes, there are also size 0 diapers for babies from 1 to 2 kg.

According to his weight

To choose the right size diaper, you must refer to your baby's weight and morphology.

As you can see on the chart, the diaper sizes overlap. In fact, weight is not the only reference you have to take into account when choosing your diapers.

According to his size

Some 5 kg babies will be comfortable in a size 2 diaper, while for other babies, it will be perfectly uncomfortable and they will prefer a size 3 diaper.

When in doubt, if your baby is in between sizes, it is best to go with the next size up.

The age is not the reference to take into account when choosing the size of diaper adapted to baby's buttocks. Each baby has his own body shape, some are smaller than others.

After 3 years: the training pants

After diapers, it's time to move on to the training pants for your baby. It's the perfect mix between a diaper and a classic underwear to help babylearn to be potty trained.

It slips on like a diaper, but has an absorbent fabric like a diaper to keep your child dry until the next change. This way, he gains freedom and is protected against all the little accidents of everyday life!

How to check that the diaper is the right size?

To make sure the diaper is the right size, here are several things to consider:

  • When a diaper is the right size, the elastic waistband reaches below your belly button;
  • In the legs, the elastic should be slightly tight;
  • When removing your baby's diaper, if you see red marks, it means that the diaper is too small.

There are several things to consider when choosing the right size diaper. First of all, you need to make sure that your baby is not too small, which could make marks on his skin and hinder his movements, and not too large, which could lead to leaks.

A tip to check that your baby's diaper is the right size: simply check that you can fit two fingers between your baby's tummy and his diaper. If the fasteners cross, it also means that the diaper is too big, and conversely if the fasteners are too close it means that the diaper is too small and that it hugs your baby too much.

As a general rule, if you don't see any leaks, you've chosen the right size.

When should I change my baby's diaper size?

As your baby grows, you need to change his diaper size. But when exactly should you change it?

There are several signs that should tell you it's time to move up to the next size:

  • If you can't fit two fingers under the waistband of the diaper after putting it on your baby;
  • If your baby's bottom is not completely covered, you can switch to the next size up;
  • If you notice red marks on your baby's tummy or thighs, it means that the diaper is too tight and that you should choose the next size up;
  • If your baby is prone to diaper rash, your diapers are probably too small;
  • If your baby himself gives you a feeling of being embarrassed by his diaper (for example if he pulls on it);
  • If the diaper's adhesive elastics reach the center of the waistband.

How many diapers does baby use each day?

A baby does not use the same number of diapers depending on his age. In fact, in the first months of his life as an infant, diapers must be changed very regularly (every two hours or so), or at each bowel movement. It is very important to change your baby's diapers regularly, as this will help prevent diaper rash and other redness that may appear on your child's bottom and/or thighs.

On average, it is estimated that during the first six months of life, diapers are changed very frequently and about six to eight times a day. This number decreases between six months and one year to five diapers per day, then to 3/4 diapers per day between one and two years, and finally to 2 to 3 until your child is potty trained.

These are all averages, of course, as every baby is different.

Are leaks related to the size of the diaper?

Leaks can happen for several reasons. Indeed:

  • If the diaper is too small or too big, so that the chosen size is wrong, leaks can happen;
  • If the size chosen is too small, the diaper will not be able to absorb all the volume of stool and urine of your baby;
  • If the diaper is too large, leaks may occur and urine and stool may leak from the sides where the diaper is not tight enough;
  • If the leg elastics are not tight enough, leakage can also occur.

What size diaper should I choose at birth?

Depending on the weight of your newborn, it is possible that a size 1 diaper is not suitable at birth. Generally, the choice is between a size 1 or 2 diaper at birth for a baby who has reached the end of his pregnancy. If ultrasounds show your baby to be healthy, consider buying a size 2 diaper in anticipation.

In any case, even if baby will wear a size 1 at the maternity hospital, this purchase will not be wasted because he will have to change sooner or later for the next size!

The FAQ of diaper sizes

How to know the size of a diaper already bought ?

The diaper sizes are indicated on the diaper packages. You will also find the average weight of a baby using these diapers, as well as the quantity in the package.

How do I know if I need to change my baby's diaper size?

Your baby grows in growth spurts. To know when to change diapers you can refer to our diaper size guide. Signs such as red marks when you change diapers should tell you that the diapers have become too small.

How do I know if my baby's diaper is too small?

If when you change your baby's diaper you see red marks on the buttocks, thighs or waistband of the diaper, it means that the diaper is too tight and therefore too small. If you also notice leaks, they may be due to a lack of absorption if the diaper is too small.

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Les informations issues des articles présents sur le site sont des informations générales. Bien qu’elles aient été relues par des professionnels de santé, ces informations ne sont pas exemptes d’erreurs, ne constituent pas des conseils de santé ou des consultations et n’ont pas vocation à fournir un diagnostic ou proposer un traitement. Ces informations ne peuvent, en aucun cas, se substituer à un avis médical et ne peuvent pas remplacer une consultation auprès d’un professionnel de santé. Pour toute question, nous vous invitons à consulter votre médecin.