Diaper size 3: until what age or weight of baby?

Your baby continues to grow very fast in the first few weeks of life and soon size 2 diapers won't fit him anymore? You wonder at what weight he can put on a size 3 diaper? When should he go up to the next size?

Everything you need to know about size 3 diapers

Size 3 diapers are for babies who weigh between 4 and 9 kg. They can be worn from the age of 3 months until about 5 to 6 months. It is at the end of the first three months of life that baby tends to slow down his growth and his weight gain.

Size 3 diapers can be worn longer than the previous sizes.

When should I start using size 3 diapers?

As with the previous size changes, there are several signs that will let you know it's time to upgrade. If you notice that:

  • Leaks are happening more and more;
  • That the absorbent surface is not large enough for your baby's size;
  • That the buttocks are no longer completely covered by the diaper;
  • That the diaper leaves red marks on your baby's skin, at the level of the thighs and the stomach;
  • If it is difficult to close the adhesives and they even tend to come off.

All of these are signs that your baby's diaper is too small and it's time to upgrade to the next size.

How many size 3 diapers should I buy for my baby?

As explained earlier, the size 3 diaper will be used much more than the size 1 or 2 diaper. So you can carry a larger supply of diapers without too much risk of not using them.

Depending on your child's weight, you will need a different number of diapers. Keep an eye on your supply so you don't end up with no diapers or too many.

The number of diapers you need will depend on your baby's weight, size and shape! You can refer to our guide below:


1st month (Nbr of packs of diapers needed)

2nd month (Nbr of packs of diapers needed)

3rd month (Nbr of diaper packs needed)

from 2,5 to 3kg

8 packs Size 1

8 packs Size 1

4 packs size 1, 4 packs size 2

from 3,1 to 3,3kg

8 packs size 1

6 packs size 1, 2 packs size 2

8 packs size 2

from 3.4 to 3.6kg

6 packs size 1, 2 packs size 2

4 packs size 1, 4 packs size 2

8 packs size 2

from 3.7 to 3.9kg

4 packs size 1, 4 packs size 2

8 packs size 2

6 packs size 2, 8 packs size 3

+ over 4kg

1 pack size 1, 7 packs size 2

8 packs size 2

8 packs size 3

How to choose the best size 3 diaper?

Beyond choosing the right size diaper for your baby, you also need to make sure that the diaper you give your baby is healthy for his skin. From birth to potty training, your baby will be wearing diapers constantly.

Therefore, your baby's diapers must be perfectly absorbent and safe.
This means making sure that the diapers do not contain toxic chemicals, endocrine disruptors, etc. that could cause irritation, rashes, diaper rash and other discomforts to your baby. To do this, you need to know the composition of the different layers of your baby's diaper: the contact layer, the absorbent material, the anti-leak material, the outer material, etc...

You must also have easy access to the analysis reports. If they are not available, move on, a lack of transparency regarding the composition of the products is never a good sign.

You should also be wary of false marketing claims or claims that are not based on reliable information. Some mentions like hypoallergenic, dermatological control are mandatory for diapers and panty liners.

Instead, refer to the whitening methods. The majority of diapers today are bleached using the ECF (Elementary Chlorine Free) method, which is a method that uses chlorine derivatives that are toxic to baby's skin. Only 5% of baby diapers are today bleached using the TCF (Totally Chlorine Free) method, which uses neither chlorine nor chlorine dioxide.

Several studies have been published by consumer associations or by the ANSS to warn about the safety of diaper compositions.

Concerning the disposable vs. cloth diapers debate, both have advantages and disadvantages. Cloth diapers are more ecological, but in terms of cleanliness and risk of irritation, disposable diapers are preferred.

Baby is growing : when to change for a size 4 diaper ?

From the 6th month of your baby's life, his weight gain continues to slow down. Here are a few signs that should tell you it's time to switch to a size 4 diaper :

  • You're seeing more and more leaks;
  • It's getting harder to close the diaper fasteners;
  • Your baby's skin has red marks from the diaper on his tummy and thighs.

And if you can't close the fasteners at all, not at all: your baby is growing and it's time to upgrade!

Les informations issues des articles présents sur le site www-elia-lingerie.com 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.