Size 1 diaper: up to what age or weight?

In collaboration with Rokiyah Hosen

Relecture professionnelle

You're getting ready for the birth of your baby, and one of the many items of childcare equipment you'll need to prepare for his arrival is diapers! Indeed, for the first few months, or even years of his life, you'll be spending a lot of time in diapers. So which size should you choose for baby? What are size 1 diapers?


Everything you need to know about size 1 diapers

Size 1 diapers generally have the same characteristics as the larger sizes! Same materials, absorption, etc... This type of absorbent product for baby's urine and stools generally consists of a skin-contact layer, leak-proof barriers, an absorbent material and a leak-proof material.

Size 1 is simply the right size for the smallest newborns, from infants to babies aged 2 to 3 months. More than just an age range, it's advisable to choose the size of diaper according to baby's weight, as not everyone has the same morphology and growth at the same age, and a baby who's lighter or bigger than his or her diaper size could leak! Size 1 diapers are therefore generally suitable for babies weighing from 2 kg to 5 kg.

When should I start using size 1 diapers?

From birth, except for very premature babies, who wear a size 0 diaper! Size 1 diapers are perfectly suited to babies weighing 2 kg or more, bearing in mind that the average birth weight varies from 2.5 kg to 4 kg: this makes size 1 the perfect candidate to fit your baby's little bottom during the first few weeks. This size 1 will therefore be ideal in the vast majority of cases: you can leave a few packs of nappies for his birth kit in his future bedroom.

How many size 1 diapers should I buy for my baby?

For the first 3 months of your baby's life, you'll need an average of 8 diapers a day. In theory, you'll need around 700 diapers!

If the medical profession predicts a large baby at birth, you can simply buy size 1 diapers for the first 2-3 weeks of life, i.e. around 150 changes, and then go straight on to size 2. It's important to know that even if you're told your newborn weighs 4kg or more at birth, and could in theory go straight up to size 2 (usually 3 to 6kg), it's normal for babies to lose an average of 10% of their birth weight in the first few days, and for them to take some time to get back into shape. At the maternity hospital, diapers are sometimes provided, but sometimes you'll have to bring them yourself: ask around to find out. For an average stay of 3-4 days, a single package in your maternity suitcase will suffice for your baby's first days of life.

When you become a mom or dad, you tend to want to foresee everything, but don't anticipate your baby's growth too quickly: there's no point in equipping yourself for more than a month's grooming, as he could overshoot his weight curve faster than expected, and you could end up with ill-fitting diapers! Bear in mind that one baby can put on weight quickly and in spurts, while others may struggle to keep up with their weight curve in the first few weeks.

On the other hand, you can store the rest of your toiletries and hygiene products, such as wipes, liniment, cleansing water, etc., for longer if you want to buy in batches. If you're worried that you won't have time to think about restocking your diapers during your post-partum period, don't hesitate to subscribe to a subscription system, most of which offer you an evolution of the sizes shipped over the months, to keep up with your offspring's growth.

Below you'll find a summary of the quantities of diapers you'll need for your child's first 100 days, based on a pack of around 30. This is purely indicative, as each child grows at his or her own pace at this age.


Expected birth weight

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 3 kg

8 packs Size 1

8 packs Size 1

4 packs size 1
4 packs size 2

from 3.1 to 3.3 kg

8 packs size 1

6 packs size 1
2 packs size 2

8 packs size 2

from 3.4 to 3.6 kg

6 packs size 1
2 packs size 2

4 packs size 1
4 packs size 2

8 packs size 2

from 3.7 to 3.9 kg

4 packs size 1
4 packs size 2

8 packs size 2

6 packs size 2
8 packs size 3

+ over 4 kg

1 pack size 1
7 packs size 2

8 packs size 2

8 packs size 3


How to choose the best size 1 baby diaper?

The best diaper for baby is the one he tolerates best! Some babies are particularly sensitive to irritation and diaper rashSo don't hesitate to change brands if you notice redness despite regular diaper changes.

Generally speaking, it's wise to say that a clean, chemical-free composition and ecological or cotton materials in contact with the skin are good indicators that a diaper is safe for baby's skin! Eco-friendly diapers made from natural materials (cotton, cellulose) are best for your baby. Don't always rely on marketing pitches, which sometimes distort reality: look for external, independent certifications to validate a product's safety. Don't forget that for the first few years of his life, your baby wears a diaper 24 hours a day, in constant contact with his sensitive skin, in a context of humidity and acidity.

When it comes to the disposable versus washable diaper debate, each has its advantages and disadvantages. In terms of cleanliness andirritation, disposable diapers, although more polluting, will be healthier for your child.

Keep an eye out for publications by ANSES (Agence Nationale de Sécurité Sanitaire) and DGCCRF (Direction Générale de la Concurrence, de la Consommation et de la Répression des Fraudes) on the safety of diaper materials. Analysis reportsshould also be available from the brand you've selected!

Last but not least, good absorption, with no leaks, is a guarantee of peace of mind for you and your child!

When to change baby's size 2 diaper?

To know when it's time to move up to the next size, here are a few clues:

  • It's getting harder and harder to get the tape to stay on the waistband, or the tape is coming off quickly;
  • Your baby seems to be tight and his skin is marked by the elastic when you change him;
  • You notice more leaks and spills (hello stains on onesies!);
  • It's no longer possible to slip two fingers between baby's tummy and his diaper.

So, baby's grown up and it's time to buy him some size 2 diapers !