Size 3 diapers: up to what age or weight?

In collaboration with Rokiyah Hosen Professional proofreading


Your baby continues to grow very fast in the first few weeks of life and soon size 2 diapers won't fit him anymore? Are you wondering at what weight he can start wearing a size 3 diaper? When should he go up a size? 


All you need to know about size 3 diapers

Size 3 diapers are for babies weighing between 4 and 9 kg. They can be worn from 3 months up to around 5 or 6 months. After the first three months of life, baby's growth and weight gain tend to slow down

Size 3 diapers can be worn longer than previous sizes.

When should I start using size 3 diapers?

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

  • More and more leaks are coming in;
  • That the absorption surface is not large enough for your baby's size;
  • That the buttocks are no longer fully covered by the diaper;
  • That the diaper leaves red marks on your baby's skin on the thighs and stomach;
  • If adhesives are difficult to close and even tend to peel off.

These are all signs that your baby's diaper is too small and that it's time to move up to the next size.

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

As explained above, a size 3 diaper will be used much more than a size 1 or 2 diaper. You can therefore carry a larger stock of diapers, without too much risk of not using them. 

Depending on your child's weight, you'll need a different number of diapers. Keep an eye on your stock so you don't find yourself without diapers or with too many.

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



1st month (No. of packs of diapers required)

2nd month (No. of packs of diapers required)

3rd month (No. of packs of diapers required)

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 baby 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 or her skin. From birth to potty training, your baby will constantly be wearing diapers.

Your baby's diapers must therefore be perfectly absorbent and harmless.
To achieve this, you need to smake sure that your baby's diapers contain no toxic chemicals, endocrine disruptors, etc. that could cause irritation, redness, diaper rash or other discomforts. To do this, you need to find out about the composition of the different layers of your baby's diaper: the contact layer, the absorbent material, the leak-proof material, the outer material, etc.

You also need easy access to analysis reports. SIf you can't access them, don't bother - a lack of transparency about product composition is never a good sign.

You should also be wary of false marketing claims or claims that are not based on reliable information. Certain labels, such as hypoallergenic and dermatologically tested , are mandatory for diapers and panty liners.

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

A number of studies have been published by consumer associations and the ANSS, warning of the safety of diaper compositions.

As for the disposable vs. cloth diaper debate, both have their advantages and disadvantages. Cloth diapers are more environmentally friendly, but in terms of cleanliness and risk of irritation, we prefer disposables.

Baby's growing: when to change to a size 4 diaper?

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

  • You are seeing leaks more and more often;
  • It becomes difficult to close the diaper fasteners;
  • Your baby's skin has red marks from his diaper, on his tummy and thighs.

And if you can't fasten the ties at all, don't worry: your baby is growing and it's time to go up a size!