Nappy Sizes Explained: The Ultimate Guide

It can be hard to know what your baby needs, especially for your firstborn, and nappies can be one area that feels a little overwhelming to new parents.

In the nappy size guide, age is not the deciding factor. Instead, your baby's weight will determine which nappy sizes to use, moving from Size 0 through to Size 6, and afterwards to nappy pants and pull-ups.  With tips on leg cuffs, weight charts and buying in bulk - follow our size guide to help you find the perfect nappy to keep your little one dry, happy and healthy. 
 

Although different brands vary slightly, most nappy size guides are worked out on the following baby weight chart:

Size 0 - weight 1 - 2.5 kg / 2 - 5 lbs

Size 1 - weight 2 - 5 kg / 5 - 11 lbs

Size 2 - weight 3 - 6 kg / 7 - 14 lbs

Size 3 - weight 4 - 9 kg / 8 - 20 lbs

Size 4 - weight 7 - 18 kg / 15 - 40 lbs

Size 5 - weight 11 - 25 kg / 24 - 55 lbs

Size 6 - weight 16 kg + / 35 lbs +

The Pampers nappy size guide varies slightly - 'Size N' is for babies under 10 lbs, which includes babies in the Size 0 and Size 1 category in the above chart. After that, the Pampers size guide follows the same pattern, differing by around 4 - 5  lbs for each of their nappies sizes, until Size 6, which is also for babies that weigh 16 kgs + /35 lbs +. The guide from Pampers has a cross-over period, where the weight ranges overlap - at this stage, parents can decide to stay at the same size or move up to the next, depending on their baby. While a long, slim baby is probably better suited to the smaller size, a rounder baby may be able to move up.

Size N - weight less than 4.5 kg / 10 lbs

Size 1 - weight 3.5 - 6.5 kg / 8 - 14 lbs

Size 2 - weight 5.5 - 8 kg / 12 -18 lbs

Size 3 - weight 7 - 12.5 kg / 16 - 28 lbs

Size 4 - weight 10 - 16 kg / 22 -35 lbs

Size 5 - weight 12 - 16 kg / 27 - 35 lbs

Size 6 - weight 16 kg + / 35 lbs +

If the tapes that you use to secure the nappy are stretched, then you should move on the next size up. The same goes if the tapes no longer reach the centre of the waistband. Marks on your baby's legs also indicate that a nappy is too small, so you may need to move on to a larger size. Another sign of a nappy that is too small is a frequent nappy rash - as the nappy is too tight to be able to effectively keep moisture away from the baby's skin.

The nappy size guide Pampers have published also notes how long a baby wears each size nappy before moving on to the next.

Size 0 (also called Size N) is typically worn for only 1 month.

Size 1 is worn for 2.5 months.

Size 2 is worn for 2.5 months.

Size 3 is worn for around 10 months.

Size 4 is worn for around 10 months.

Size 5 is worn for around 14 months.

Size 6 is worn for around 14 months.

It is easier than ever to find a nappy that is designed for premature or low-birth-weight babies. Plenty of brands now offer 'Preemie' nappies, or otherwise 'Size 0' may be small enough to keep baby dry and happy.

Keeping baby dry is essential for a happy baby, and a nappy that fits properly is naturally more effective at keeping leaks at bay. Read our checklist to ensure a leak-free nappy:

A snug waistband is key, though it should never feel tight or constricting around your baby's tummy. You should be able to fit two fingers under the waistband

You should not see red marks or indentations when you take the nappy off. This indicated that it is too tight.

The waistband should sit just below the belly button.

Make sure that you secure the waist tapes symmetrically, so that the nappy sits evenly on both sides.

Stretch the leg cuffs neatly around the baby's thighs by running two fingers under the cuff once the nappy is on.

Using the right size nappy will also ensure fewer leaks, as nappies that are too big will have gaps and nappies that are too small will not be absorbent enough.

Look for a nappy that has 'Plus' or a '+' sign, as these are designed to be more absorbent and are a good choice for night time.

-Before the birth of your baby, it can be a good idea to buy two packs of nappies: one for newborns and one for the next size up.

-Do not open nappies until you need to use them, and keep the receipt as many shops will allow you to swap for a different size.

-It is more cost-effective to buy large packs of nappies, but it can be a good idea to swap to smaller packs when your baby is getting near to needing the next size up.

-Nappies for premature and newborn babies have an extra design feature; a U-shape cut from the front that doesn't interfere with the umbilical cord.

-Some parents find that they can use cheaper nappies during the day, but most agree that it is worth using a higher quality, super absorbent nappy overnight.

-Experiment with different brands, as one may work much better for you than the others.

-Size 0 - Size 4 nappies tend to focus on absorbency and dryness, whilst nappies for older, more active babies offer designs that are called 'active fit' or 'active stretch'. After that, your little one will wear nappy pants, pull-up and easy-up nappies.