Diaper size 4: until what age or weight of baby?

Your baby is still growing and you are having more and more difficulty closing his size 3 diaper? Are you wondering at what age and weight size 4 corresponds? We explain everything you need to know about this diaper size in this article.

Everything you need to know about size 4 diapers

The size 4 baby diaper is designed for babies weighing between 7 and 18kg. This corresponds to babies from 6 months to about 18 months.

After 6 months, your baby's growth and weight gain slows down. The size 4 diaper is worn longer than the previous sizes.

When should I start using size 4 diapers?

As soon as the size 3 diaper diaper becomes too small, you can switch to size 4 diapers. How do you know if a diaper is too small?

If you can fit two fingers between the diaper and your baby's tummy, it means that the size 3 diaper is still suitable for your child. But, if you're having trouble, it may be a sign that it's time to switch to the next size up and that the size 3 diaper is no longer appropriate.

There are several other indicators that may alert you to the fact that the diaper is probably too small now.

If you are experiencing increasingly frequent leaksIf you are experiencing increasingly frequent leaks, it means that the absorbent surface is no longer large enough for your baby's size and shape.

In this case, switch to size 4. The same thing happens if you notice that your baby's skin is marked with red marks when you change him.

How many size 4 diapers should I buy for my baby?

As explained before, size 4 diapers are the size that your baby will wear the most. It is therefore quite possible to order several packages in advance, they will most likely all be used.

To reduce your mental load related to diaper purchases, you can opt for a subscription that will allow you to receive your diapers where and when you want.

Our table below summarizes the quantities of diapers to buy according to the size and age of the baby, for each diaper size. Of course, this can vary from one child to another:


Number of packages in size 3

Number of packages in size 4

Number of packages in size 5

from 5 to 7 kg


from 7,1 to 7,5kg



from 7,6 to 9,9kg


from 10 to 10,5kg



+ more than 10,5kg


How to choose the best size 4 diaper?

Your baby should feel comfortable in his diaper, as much by the size you choose as by the quality of the diaper itself.

Indeed, the diapers are directly and permanently in contact with your baby's skin, until he becomes clean. It is therefore important for your child to choose healthy, soft diapers, in which he feels comfortable and with a good support.

To have healthy diapers, it is essential to look at the composition of the diaper. You have to make sure that the diapers will not contain toxic chemicals, endocrine disruptors, perfume, latex or chlorine. To ensure the right composition, you should also look at the bleaching method used. Most diapers are bleached using the ECF (Elementary Chlorine Free) method which uses chlorine derivatives. These chlorine derivatives are toxic for your baby's skin which is very delicate.

5% of the diapers are bleached according to the TCF (Totally Chlorine Free) method. This method guarantees that the diapers have been bleached without chlorine or chlorine dioxide. This is the healthiest method for your baby.

To have a quality product, it is preferable to choose disposable and ecological diapers. In general, they pay more attention to the composition of their products by adopting natural materials, renewable materials etc...

Ecological and natural diapers are not less absorbent than conventional diapers. They will simply use synthetic materials for the absorbent part while ecological diapers will turn to cellulose of natural origin.

Also beware of marketing claims such as hypoallergenic, dermatologist tested, etc., these are mandatory claims thatdo not guarantee the non-toxicity of the diapers .

Baby is growing: when to change to a size 5 diaper?

Same thing as when you have to change your diaper for a size 4, if you observe more and more frequent leaks, that you can't close the fasteners anymore, that your baby's skin has red marks when you change his diaper, it means that his diaper is too small. You can then turn to size 5 diapers.

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.