The Complete Guide to Diaper Sizes

With a million and one things to learn as a new parent, something that’s good to get ahead of is knowing your diaper sizes — and getting your stash prepared! Just like with clothing, different brands may sell the same sizing, but their fit might be different. And just like adults, babies might be the same weight or age but have different body shapes. So don’t despair if you don’t get it right immediately. It can take a little bit of trial and error to find the diaper size, and style, that best fits your baby’s precious bum… and we apologize in advance for any blowouts that you might have to go through before you get it 100% nailed.

How do you know what size diapers to get?

Different brands might have different names, but generally, they all play by the same rules when it comes to naming baby diaper sizes. Most newborns will, surprise surprise, fit into the “newborn” size at birth, but will quickly grow out of them, so it’s a good idea to get some size one diapers ready too.

What are the sizes of diapers?

You’ll find diaper sizes by weight, rather than diaper size by age, which helps get a better fit. Some diaper sizes will overlap, so you can make a choice based on your baby’s body. Longer, slimmer babies, for example, might fit into a smaller size for longer than a slightly chubbier baby.

So, what are diaper sizes?

You’ll often find a handy diaper size chart on the packaging, which will probably follow these guidelines:

Preemie — up to six lb (only available in certain brands like Huggies or Pampers diaper sizes) Newborn — up to 10lb Size 1 — 8-14 lb Size 2 — 12-18 lb Size 3 — 16-28 lb Size 4 — 22-37 lb Size 5 — over 27 lb Size 6 — over 35 lb Size 7 — over 41 lb (only available from certain brands).

What diaper size is most common?

Usually, babies will go through sizes one and two within the first six months, but your baby might be in size three and/or four for much longer. These tend to be the most popular sizes. These sizes are often available in pull-up styles too, which can make diaper changes easier as your baby grows into a toddler.

How many diapers do I need?

Newborns will need eight to ten diaper changes per 24 hours. So even though they may grow out of newborn diapers in a month, you may still need 300 of them. Yikes. Your baby will need fewer changes per day as they get older though! Phew!

And if you're worried about diapers expiring, there's nothing to worry about. The three year manufacturing expiry date is just a suggestion.

When to change diaper sizes

Getting the right diaper fit is important to make sure your baby is comfortable, and you’re not having to deal with too many poo-namis (that’s a “tsunami” of… well, you get it). There will be some tell-tale signs your baby might be ready to size up in the diaper department, such as:

• The fasteners no longer meet in the middle of the waistband without it being too tight.
• Your baby is getting frequent diaper rash from moisture being held too close to their skin.
• The diaper doesn’t fully cover their bottom.
• The fasteners pop open frequently when your baby moves around.
• You get leaks and poop explosions (this might also be a sign of a too-big diaper, sorry!).
• Your baby seems uncomfortable and might pull at the diaper.
• There are red marks around their legs or tummy when you remove the diaper.

Are there size 8 diapers?

You might find some larger-size diapers (size eight) designed for children who have potty-trained but still need a diaper overnight, or for those with disabilities. But most mainstream brands max out at size six or seven, which will generally get you through to potty training age.

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