How to Choose the Right Eco Nappy Size for Your Baby
, by Hello Charlie Blogs, 3 min reading time
Choosing the right nappy size sounds simple, but it can be surprisingly confusing.
Babies do not grow in perfect size charts. Some have chunky thighs, some have slim waists, some are long and lean, and some sit between two sizes for weeks.
The right nappy size should fit comfortably, contain wees and poos, and move with your baby without digging in or leaking.
This guide explains how to choose eco nappy sizes, when to move up, and what to do if your baby’s nappy keeps leaking.
Start with the weight guide
Most disposable nappies include a weight range on the pack.
This is the best place to start, but it is not the only thing that matters. A baby at the top of one size range may still fit that size well, while another baby may need to move up earlier because of their shape or absorbency needs.
You can browse current options in our Eco Disposable Nappies collection, including brands such as Muumi Eco Nappies and Bambo Nature.
Signs the nappy is too small
Your baby may need the next size up if:
- The nappy leaves deep red marks around the legs or waist.
- The tabs are stretching too far to fasten.
- The nappy looks low at the back.
- You are getting frequent leaks.
- The absorbent area seems too narrow.
- Your baby seems uncomfortable in the nappy.
Leaks are not always a size issue, but frequent leaks are a good reason to check fit.
Signs the nappy is too big
A nappy that is too large can also leak.
Signs include:
- Gaps around the legs
- The nappy sitting too high or bulky
- Loose waistband
- Tabs crossing too far over each other
- Leaks before the nappy is very wet
If the nappy gaps around the legs, it may not seal well enough to contain mess.
Check the leg cuffs
After putting on a disposable nappy, gently run your finger around the leg cuffs to make sure they are pulled out, not tucked inside.
Tucked-in leg cuffs are one of the easiest causes of leaks.
The nappy should sit smoothly around the thighs without digging in.
Day nappies vs night nappies
Your baby might fit one size during the day but need more absorbency overnight.
Before moving up a full size, ask:
- Is the nappy completely full in the morning?
- Is your baby sleeping longer stretches?
- Are leaks only happening overnight?
- Do you need a more absorbent nappy rather than a larger nappy?
You can browse bulk and overnight-friendly options in our Bulk Nappies and Eco Disposables Packs collections.
Nappies vs nappy pants
Standard nappies usually work well for newborns and younger babies.
Nappy pants or pull-ups can be helpful when babies become wriggly, start crawling, or move into toilet training. They are easier to pull up and down, but they still need to fit snugly around the waist and legs.
You can browse Toilet Training Pants for older babies and toddlers.
Try samples before buying bulk
Eco nappies can vary in fit between brands.
Before buying a bulk box, it is worth trying a smaller pack or sample if you are unsure. This is especially helpful if your baby is between sizes or has had leaks with another brand.
Hello Charlie’s Eco Nappies Samples are a practical way to test fit before committing.
Final thoughts
The right nappy size is not just about the number on the pack.
Check the weight guide, but also look at your baby’s shape, comfort, absorbency needs and leak patterns.
If you are unsure, try a small pack first, check the leg cuffs and move up when the nappy starts leaving marks or leaking regularly.
You can browse Eco Disposable Nappies, Muumi Eco Nappies, Bambo Nature and Eco Nappy Samples, or read more on the Hello Charlie Blog.