The Complete Diaper Size Guide: Chart of Most Popular Brands

Diapers to babies are like bras to women: a little annoying, pretty essential and you’re likely to buy the wrong size. With so much at stake with our little ones and their explosive bowels, it’s important to find the right size of diaper for your little pooper. 

While a diaper fitting service in-store would be perfect – try before you buy – it’s not gonna happen, and that’s pretty gross, actually. So it’s down to diaper size guides to tell us what size we should expect our babies to be wearing. Here’s the lowdown on the most popular diaper brands of 2020, their sizes, and how to choose the right one for your little one. 

Good luck out there, parents!

How do diaper sizes work?

Unlike baby and children’s clothes, which are usually sized by age, diapers are generally sized by weight. That’s not to say that if your little one ‘should’ be in a certain size according to the brand’s size chart, that it’ll definitely fit, but it should be about right. 

Diaper sizes generally go from newborn or size 0 to size 6, which covers babies from birth to when they’re a chunky 35lbs or more. And training pants and pull-ups are available for potty training toddlers, which might be sized by weight, or by age. 

You’ll probably be surprised at how quickly your baby moves up in diaper size. One minute they’re a newborn bundle of joy, the next they’re a much larger, much noisier bundle of energy. And joy, of course. So while it’s usually worth buying in bulk to save those dollars, remember that your baby will grow very quickly. Buying too many of one size is a recipe for lots of wasted cash!

Diaper Sizes by Weight and Age

While diapers are usually sized by weight, it’s handy to know what size your baby is likely to need at certain stages of their development. Here’s a general overview:

Diaper SizeWeightAge
NewbornUp to 10lbsThe first 2 or 3 weeks
Size 18-14lbsBirth – 4 months
Size 212-18lbs3 – 8 months
Size 316-28lbs5 – 24 months
Size 422-37lbs18-36 months
Size 527lbs+3 years +
Size 635lbs+4 years +

Disposable Diapers Sizes

Disposable diapers are the order of the day for most parents and carers. Ease and convenience make disposables very appealing to new and experienced parents alike, but this isn’t great news for the planet, nor for our little ones’ delicate skin. Most diaper brands are made with petroleum-based plastic and contain chemicals that leave a lot to be desired when it comes to health. 

Chlorine, phthalates, fragrances, lotions, and dyes made with heavy metals should be avoided wherever possible, and there are actually lots of companies paving the way to a healthier diaper future, like Bambo Nature, Dyper, and Hello Bello. Bonus points if that diaper is made from plant-based materials, like bamboo, wood, or cane, and can be composted. While the average disposable diaper will take hundreds of years to break down, natural biodegradable diapers will begin this process within months. 

Read more about what’s inside disposable diapers for more information on these harmful toxins, and check out my favorite non-toxic and biodegradable diapers!

Bambo Nature Size Chart

Bambo Nature is a great eco-friendly diaper company. They offer super soft bamboo diapers that are free of toxins and hypoallergenic. 

SizeWeight Range
Size 14-11 lbs.
Size 27-13 lbs.
Size 39-20 lbs.
Size 415-40 lbs.
Size 524-55 lbs.
Size 633-66 lbs.

Dyper Size Chart

Dyper is another amazing company revolutionizing the disposable diaper market. Their non-toxic bamboo diapers are soft and effective, and the company even purchases carbon offsets with each diaper delivery.

SizeWeight Range
Small6-16lbs
Medium13-22lbs
Large20-31lbs
X Large 28lbs+

Hello Bello Size Chart

Founded by the uber-famous actress Kristen Bell, Hello Bello diapers are free of toxins and kinder to the planet, with mainly plant-based materials. They offer a subscription service for diapers straight to your door and have great reviews.

SizeWeight Range
NewbornUp to 10lbs
Size 18-12lbs
Size 210-16lbs
Size 314-24lbs
Size 422-37lbs
Size 527lbs+
Size 635lbs+

Honest Diapers Size Chart

I’m not sure what’s in the water in Hollywood, but it seems to be encouraging A-list actresses to turn their hands to diaper manufacturing! It’s Jessica Alba’s turn to show us what non-toxic diapers should look like. Honest diapers are a popular skin-friendly brand, with some super cute designs. They’re made with chlorine-free wood pulp and free from toxins like phthalates, fragrances, and lotions.

SizeWeight Range
NewbornUp to 10lbs
Size 18-14lbs
Size 212-18lbs
Size 316-28lbs
Size 422-37lbs
Size 527lbs+
Size 635lbs+

Huggies Little Movers Size Chart

Little Movers are for babies on the go. Designed to keep your little one dry while they’re wriggling, crawling, and exploring, they have plenty of fancy features like double grip strips, a contoured shape, and a wetness indicator. The problem with big brands like Huggies and Pampers, though, is that they appear to use toxins in their products, and aren’t making much of an effort currently to go green!

SizeWeight Range
Size 316-28lbs
Size 422-37lbs
Size 527lbs+
Size 635lbs+

Huggies Little Snugglers Size Chart

Little Snugglers are designed to be… snuggly, I guess. Soft on your baby’s skin, they’re good for newborns, are hypoallergenic, and have a wetness indicator for changing without guesswork.

SizeWeight Range
Preemie1-5lbs
Newborn6-9lbs
Size 18-14lbs
Size 212-18lbs
Size 316-28lbs
Size 422-37lbs
Size 527lbs+
Size 635lbs+

Huggies Snug & Dry Size Chart

Huggies’ Snug & Dry variety promises up to 12 hours of dryness, so they’re suitable for overnight. Their wide range of sizes means they’re suitable for most stages of your baby’s diaper-wearing journey.

SizeWeight Range
Newborn6-9 lbs.
Size 18-14 lbs.
Size 212-18 lbs.
Size 316-28 lbs.
Size 422-37 lbs.
Size 527+ lbs.
Size 635+ lbs.

Kirkland Diapers Size Chart

Available at Costco, Kirkland diapers are made with ‘at least 23%’ plant-based materials, claim to be super absorbent, and are very budget-friendly.

SizeWeight Range
Size 1Up to 14 lbs.
Size 212-18 lbs.
Size 316-28 lbs.
Size 422-37 lbs.
Size 527+ lbs.
Size 635+ lbs.

Luvs Ultra Leakguards Size Chart

Luvs diapers are another budget-friendly option and they’re widely available. Made predominantly with petroleum-based plastics, they don’t boast of being free of any toxins, so I assume they’re used.

SizeWeight Range
NewbornUp to 10 lbs.
Size 18-14 lbs.
Size 212-18 lbs.
Size 316-28 lbs.
Size 422-37 lbs.
Size 52+ 7lbs.
Size 635+ lbs.

Mama Bear Size Chart

Mama Bear diapers are a fantastic choice for those on a budget. While their Best Fit diapers don’t boast any eco-credentials, their Gentle Touch variety is chlorine, fragrance, lotion, and phthalate-free. Plus, they’re produced in a zero waste to landfill facility.

SizeWeight Range
NewbornUp to 10 lbs.
Size 18-14 lbs.
Size 212-18lbs.
Size 316-28lbs.
Size 422-37lbs.
Size 527+ lbs.
Size 635+ lbs.

Pampers Cruisers Size Chart

Like Huggies Little Movers, Pampers Cruisers are for babies on the move. They adapt to your baby’s body, keeping them dry while they explore the world around them.

SizeWeight Range
Size 316-28 lbs.
Size 422-37 lbs.
Size 527+ lbs.
Size 635+ lbs.
Size 741+ lbs.

Pampers Pure Size Chart

Pampers Pure are the brand’s ‘eco-friendly’ variety. Made with cotton, they avoid chlorine, but it looks like they contain other toxins like phthalates, fragrances, and lotions.

SizeWeight Range
NewbornUp to 10 lbs.
Size 18-14 lbs.
Size 212-18 lbs.
Size 316-28 lbs.
Size 422-37 lbs.
Size 527+ lbs.
Size 635+ lbs.

Pampers Swaddlers Size Chart 

Pampers Swaddlers are the number 1 choice for parents and hospitals in the US. They have great reviews, but unfortunately no eco-credentials.

SizeWeight Range
NewbornUp to 10 lbs.
Size 0Less than 10 lbs.
Size 18-14 lbs.
Size 212-18 lbs.
Size 316-28 lbs.
Size 422-37 lbs.
Size 527+ lbs.
Size 635+ lbs.
Size 741+ lbs.

Seventh Generation Size Chart

Seventh Generation are probably the most well-known ‘eco’ diaper brand. They’re certainly not the best – their use of phthalates is unclear – but they’re widely available and made with sustainably harvested plant-based pulp.

SizeWeight Range
NewbornUp to 10lbs.
Size 18-14 lbs.
Size 212-18 lbs.
Size 316-21 lbs.
Size 420-32 lbs.
Size 527-35 lbs.
Size 635 lbs+

Overnight Diaper Sizes

Sometimes, a regular diaper just won’t cut it. If you’d rather not change your baby’s diaper a few times during the night and want to encourage them to sleep soundly, an overnight diaper might be the way to go. They’re specifically designed to be super absorbent and comfortable, letting your baby focus on getting some much-needed rest. 

GoodNites Bedtime Underwear Size Chart

The number 1 nighttime protection pants, GoodNites do what they say on the tin. Perfect for toddlers who are potty-training, they produce pretty cute designs that your little one will enjoy wearing.

SizeWeight Range
Size XS28-45 lbs.
Size S/M38-65 lbs.
Size L/XL60-125 lbs.

Honest Overnights Size Chart

A great eco-friendly alternative to most plastic-based overnight diapers, Honest offers us a plant-based, non-toxic diaper that will keep your baby dry and secure throughout the night. So it’s not just them who’ll get a good night’s rest; it’s you too! 

SizeWeight Range
Size 316-28 lb
Size 422-37 lb
Size 527+ lb
Size 635+ lb

Huggies Overnites Size Chart

Designed to keep your baby dry for 12 hours – and hopefully afford them a good night’s rest, Huggies Overnites have ‘pajama-like’ softness. 

SizeWeight Range
Size 316-28 lb
Size 422-37 lb
Size 527+ lb
Size 635+ lb

Pampers UnderJams Size Chart

Pampers UnderJams claim to absorb 20% more wetness than the ‘leading national brand’ and are made with a cloth-like material that’s comfortable for your toddler. 

SizeWeight Range
Size S/M38-65 lb
Size L/XL58-85 lb

Parent’s Choice Overnight Diapers Size Chart

Parent’s Choice also offers an overnight diaper, for up to 12 hours of protection. They’re pretty budget-friendly, but they don’t have any eco-friendly practices or avoidance of toxins to shout about.

SizeWeight Range
Size 422-37 lb
Size 527+ lb
Size 635+ lb

Seventh Generation Baby Free & Clear Overnight Size Guide

Like their original diapers, Seventh Generation Overnight diapers are made with totally chlorine-free wood fluff pulp. They’re also free of lotions and fragrances, but there’s still no word on the use of phthalates.

SizeWeight Range
Size 422-32 lb
Size 527-35 lb
Size 635+ lb

Swim Diapers Sizes

Hoping your baby might be the next Michael Phelps? You’re gonna need some swim diapers. 

Regular diapers just won’t cut it in the pool; they’ll soak up lots of water and get super heavy and uncomfortable for your little one. And there’s no way they’ll be protecting everyone else in the pool from your baby’s poops. Swim diapers are designed to keep their messes at bay while keeping your baby comfortable as she splashes her way to victory!

You can buy disposable swim diapers which can be thrown away after one use, or go for the much more environmentally-friendly option, the reusable swim diaper. These often come in one size and can be adjusted to fit your baby, whether they’re still a tiny bundle or an ever-growing toddler. 

Alvababy Swim Diapers Size Chart

Alvababy is a great reusable diaper brand. Their swim diaper offerings come in the cutest patterns, and one size fits babies from 10-40lbs!

SizeWeight Range
One size10-40 lb

Babyganics Swim Pants Size Chart

Babyganics’ swim diapers are made with (mostly) sustainable materials and provide UPF protection. They don’t swell in water and are comfortable for your baby.

SizeWeight Range
Size Small16-26 lb
Size Medium24-34 lb
Size Large32+ lb

Huggies Little Swimmers Size Chart

The number 1 selling swim diaper, Huggies Little Swimmers keep leaks at bay and are easy to adjust. They’re only available for little ones from 16lbs though, so you’ll have to look elsewhere if you want to take a younger baby for a splash!

SizeWeight Range
Size 316-26 lb
Size 424-34 lb
Size 5/633+ lb

Nageuret Swim Diaper Size Chart

These one-size diapers are a great alternative to disposable swim diapers. They fit little ones from 0-3 years, and, if you go swimming regularly, you’re sure to save money in the long run compared to buying disposables.

SizeWeight Range
One size8-35 lb

Pampers Splashers Swim Diapers Size Chart

Like Huggies Little Swimmers, Pampers Splashers have easy tear sides and a comfortable fit. They’ll fit your baby like swimwear and do have some nice patterns. Like all Pampers and Huggies varieties though, apart from a couple of eco-friendlier options, they don’t boast any eco-credentials.

SizeWeight Range
Size Small13-24 lb
Size Medium20-33 lb
Size Large31+ lb

Wegreeco Reusable Baby Swim Diaper Size Chart

Another great planet-friendly option, Wegreeco offers small and large swim diapers, which can be reused again and again. They have great reviews, so they must be doing something right!

SizeWeight Range
Size Small10-19 lb
Size Large20-40 lb

Cloth Diapers Sizes

Gone are the days of cloth and pins. The idea of reusable diapers isn’t so scary anymore, although it undoubtedly takes a little more getting used to than sticking with disposables. Cloth or reusable diapers are certainly a more eco-friendly alternative to plastic, toxic disposable diapers. They’re more expensive initially of course – you’ll need a fair few to get started – but they can save you money in the long run. 

Just be careful when it comes to washing and drying. Washing on a super high heat and using a dryer will ramp up your energy bills. It’s much better for the environment, and for your bank balance, to line dry if you can. And disposable biodegradable diapers are also a green alternative, which you could use instead of cloth diapers, or as well as.

Alvababy Baby Cloth Diapers Size Chart

One of the bestselling cloth diapers available, Alvababy is a great value reusable diaper. Available in one size for all diaper-wearing stages, they also come with a 1-year guarantee.

SizeWeight Range
One size6.6-33 lb

Babygoal Diapers Size Chart

Babygoal’s one-size cloth diapers will fit little ones from 7-33lbs. While it’s more expensive to buy cloth diapers initially, it can save you money in the long term. Babygoal’s offerings are crazy cute and include bamboo inserts.

SizeWeight Range
One size7-33 lb

BumGenius Freetime Size Chart

Bum Genius’s Freetime diapers feature a soft, stay-dry interior with an extra layer of microfiber in the shell for absorbency. They’re designed to fit babies little and large.

SizeWeight Range
One size8-35 lb

Charlie Banana Cloth Diaper Size Chart

Charlie Banana’s cloth diapers are ‘climate-neutral certified’ – they fully offset their carbon footprint and donate 1% of sales to conservation causes. They’re certainly going the extra mile when it comes to being eco-friendly!

SizeWeight Range
One size6-35 lb

GroVia Reusable Hybrid Size Chart

GroVia hybrid reusable diapers feature some seriously fancy artwork and sales from this one-size planet-saving diaper helps to ‘further the US Forest Service’s national campaign to prevent wildfires’. Not bad for a reusable diaper!

SizeWeight Range
One size10-35+ lb

OsoCozy Prefolds Size Chart

Osocozy truly goes back to basics with their natural cloth diapers. Super soft and absorbent, their smaller size is suitable for babies 7-15lbs and their larger size covers 14-30lbs.

SizeWeight Range
Small7-15 lb
Large14-30 lb

Rumparooz by Kanga Care Pocket Diaper Size Chart

These award-winning reusable diapers will also suit little ones from birth to toilet training! There are loads of designs to choose from, which is definitely the fun part.

SizeWeight Range
One size6-35 lb

Pull up Diaper Sizes

Pull up diapers are perfect for older babies and toddlers. Not only are they easy for you and your little one to put on, but they often look like ‘regular’ underwear, which certainly helps with potty training.

Bambo Nature Training Pants Size Chart

Like all Bambo Nature diapers, their training pants are free of toxins and irritants, so they’re very kind to the skin and to the planet. Their three-layer design can cope with multiple wettings.

SizeWeight Range
Size 526-44 lb
Size 640+ lb

Eco by Naty Pull Ups Size Chart

Eco by Naty’s pull up pants are certified vegan and available in larger sizes. Made from plant-based materials, they’re one of the better-known eco disposable diaper brands.

SizeWeight Range
Size 418-33 lb
Size 526-40 lb
Size 635+ lbs

Huggies Little Movers Slip-On Size Chart 

Like their ‘regular’ counterparts, Huggies Little Movers Slip Ons keep your baby dry while they’re off exploring. They’re easy to get on and off, too.

SizeWeight Range
Size 422-37 lb
Size 527+ lb
Size 635+ lb

Huggies Pull-Ups Training Pants Size Chart

Huggies Pull-Ups offer a soft waistband and fun prints that toddlers and children will love. They protect overnight, but, again, their (lack of) attempts to be eco-friendly leave a lot to be desired.

SizeWeight Range
2-4 years 27-35lbs+

Pampers Easy Ups Size Chart

Like Huggies Pull-Ups, Pampers Easy Ups are produced with fun prints for children and feature a soft, stretchy waistband for your little one’s comfort. 

SizeWeight Range
Size 4 16-34 lb
Size 5 30-40 lb
Size 6 37+ lb

When to switch to the next diaper size

How do you know when your baby needs to go up a diaper size? Here are a few signs to look out for, which might indicate the need for a larger diaper:

  1. Frequent blowouts

Frequent blowouts, annoyingly, could indicate that the diaper is too big or too small. Leaks are a given if the diaper’s too big, as it’s easy for the pee and poop to seep out of the sides. But small diapers can create the same problem, as there’s not enough room in the diaper to keep it all in.

  1. Marks on your baby’s skin

If your diaper is leaving marks on baby’s skin, it might be an indication that it’s too small. Your baby needs to be protected, but comfortable.

  1. Your baby is restricted

If your baby can’t move freely and comfortably in their diaper, it’s probably too small. It’s important for their development to move around, explore and cause absolute chaos, so they’ll need a diaper that isn’t too tight around the waist or legs.

  1. You can’t close the tabs!

The obvious clue is when you go to secure the diaper, and you’re struggling to make it fit! It’s time for the size up.

Frequently Asked Questions About Diaper Sizing

1. What do I do if newborn diapers are too small for my baby, and size 1 is too big?

If you’re finding that your newborn diaper is on the small side, but size 1 is still that little bit too big, there are two things you could do. The first is to try folding down the waist of the size 1 diaper before you use it, to see if that makes it more secure. If that doesn’t work, it might just be that the brand isn’t quite right for your baby. Just because your baby fits into the weight category of a certain size, doesn’t mean that a diaper will fit perfectly. Every little one is different, so trying another brand should do the trick. 

2. When should I switch to size 3 diapers?

Size 2 diapers are generally suitable for babies between 12 and 18 pounds and size 3s are usually suitable for babies between 16 and 28 pounds. So if your baby is coming up to the 16-18lb mark and you’re getting frequent leaks or blowouts, it might be time to make the switch to size 3. 

3. How do I know if a diaper is too big?

There are several signs that your baby’s diaper might be a bit too big:

  • Sagging: If the diaper doesn’t look or feel very secure, and it sags too low, it’s probably too big. Sagging and an insecure fit is a perfect recipe for leaks and blowouts.
  • Leaks and blowouts: If you’re frequently experiencing leaks and poop explosions, it may be that the diaper is too big, so it’s easily ‘letting out’ your baby’s waste.
  • It doesn’t fit around the waist: If there’s a big gap between the diaper and your baby’s waist, the diaper’s probably too big.
  • The leg cuffs aren’t secure: If the leg cuffs aren’t very secure, the diaper’s probably too big, and you’re gonna get some leaks. Try a smaller size.

4. What should I do with diapers that are too small?

Disposable diapers are pretty terrible for the environment as it is. So if you find yourself with extra diapers because your baby’s grown out of them, you could offer them to a friend with a little one, sell them online or donate them to a local charity or refuge for women. Diapers aren’t the cheapest, so any donations to those in need are sure to be very gratefully received.

5. How long do babies stay in size 2 diapers?

How long your little one will need size 2 diapers will vary from baby to baby. But, suffice to say, babies don’t stay little for very long, and you’ll be surprised at how quickly they grow out of diaper sizes! You’re likely to need size 2 diapers for a couple of months at least, but it’s best to be guided by your baby’s size and weight. 

6. Why do diaper blowouts happen?

There are three reasons why blowouts happen: your baby is wearing the wrong size, the diaper just isn’t very effective or it’s a particularly big poop explosion that even the toughest of diapers couldn’t handle. Poop explosions, luckily, shouldn’t be an everyday thing, but if you are experiencing frequent blowouts, it’s probably because your baby’s wearing the wrong size. Of course, if you go up or down a size and you’re still experiencing them, it might be time to try another brand!

If your baby is getting more pee and poop on their clothes/you/the changing mat than in their diaper, try a smaller or larger size. It’s definitely better for your bank balance to buy in bulk, but when you’re trying a new size, it’s worth buying a smaller pack, just in case you’re not happy with the brand or size.

Finding the right diaper is the key to preventing blowouts and poop explosions… apart from the inevitable deluge when your little one hasn’t ‘gone’ in a couple of days. And you’ll wonder how something so adorable can produce such poop volcanoes. They manage it, somehow.

7. At what age should a baby be in size 2 diapers?

Sizing by age isn’t a hard and fast rule, because it really depends on your baby’s size and weight. After all, most newborns weigh somewhere between 5lbs and 12lbs, so they’ll all move up a size at different times. But you can expect your baby to be in size 2 diapers at some stage between 3 months and 8 months old.

8. What are the sizes of Pampers?

All Pampers diaper varieties seem to follow the same size guide:

SizeWeight Range
NewbornUp to 10 lb
Size 18-14 lb
Size 212-18 lb
Size 316-28 lb
Size 422-37 lb
Size 527+ lb
Size 635+ lb

Not all of their varieties are available in all sizes, though. Their cruisers variety starts from size 3, as they’re made for slightly older, and slightly wrigglier babies! It’s still worth checking the pack and the brand’s site if switching varieties, of course.

9. Are diapers sizes universal?

While some brands tend to share similar size charts, diaper sizes certainly aren’t universal, and vary from country to country and brand to brand. Whenever you’re switching to a new kind of diaper, check the box or the brand’s site for their sizing. It could be completely different from what you’re used to!

10. What is the average size diaper for a 1-year-old?

The average 1-year-old baby boy in the US weighs just over 21lbs and the average 1-year-old girl weighs just under 20lbs. Given that size 3 diapers tend to be suitable for babies weighing between 16 and 28lbs, it’s likely that the average 1 year old will be in either size 3 or 4 diapers. Size 4 tends to be recommended for 22-37lbs babies, so those who weigh slightly more than average are probably in the bigger size. This is all based on averages, of course, and our little ones are anything but! 

11. What is the weight for a size 2 diaper?

The recommended weight for size 2 diapers tends to be 12-18lbs. This guidance will vary from brand to brand, but if your little one is in this weight range, size 2 diapers will most likely be the correct size.

12. At what age should a baby be in size 4 diapers?

Size 4 diapers are usually for babies (or toddlers, really!) who weigh between 22 and 37lbs. The average 15-month-old boy in the US weighs just under 23lbs and the average girl, just over 21lbs. They’re not likely to hit 37lbs until they’re about 4 and a half, so the age range for size 4 diapers is pretty big – between 15 months and 4.5 years. On the higher end of that weight scale, a parent might need to look at size 5s or 6s, depending on the size of their toddler or child.

The bottom line

Diaper sizes can be a minefield, but this guide should help you to decide what size is right for your baby. It’s still super important to check each individual brand, as they can vary. 

The right diaper size makes for a very happy baby and a very happy parent. Your baby will have the freedom to wriggle, crawl, and walk to their heart’s content, with that hard-working diaper keeping the pee and poop at bay. And you’ll be happy because – well – the pee and poop is being kept at bay. The wrong size, on the other hand, makes for some pretty messy scenes indeed: the kind of ‘just-put-them-straight-in-the-bath’ scenes. 

Ultimately, if a diaper isn’t working for you and the sizing isn’t the issue, simply switch brands. There are so many amazing diaper companies out there producing epic environmentally-friendly and skin-friendly diapers for all shapes and sizes, that you shouldn’t have any trouble finding the perfect fit. 

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