How to find the right diaper size for your baby (2024)

If you find yourself overwhelmed by the diaper aisle – do you pick one based on your baby’s weight or how many weeks old they are? – you're not alone. Diapers are confusing! “Am I the only one who thinks that diaper size pounds are not very accurate?,” says one BabyCenter mom.

The reality is, no two babies are alike, so everyone's diaper journey will be slightly different. “Picking a diaper size for your baby is like finding the perfect pair of jeans: No one size or brand fits everyone, and you have to try it on first,” says Chandani DeZure, M.D., a pediatrician and BabyCenter Medical Advisor. “Parents can use the reference weight on the packaging as a guide and then after ‘trying it on,’ determine which diaper size fits their baby best.” However, there are some things to watch for, so here's what the experts say when it comes to disposable diapers.

What to look for in a diaper

Ultimately, you want to find a diaper that works well for your baby. “Diapers need to fit appropriately, prevent leakage, and be comfortable for your baby,” says Dr. DeZure. “So the size can't be too small or too large, can't have pee or poop leaking out from the sides with typical use, and can't cause chafing or rashes.” But how do you find a disposable diaper that checks all the boxes? Here's what to consider:

• The material they're made out of: The variations and materials are seemingly endless when it comes to disposable diapers. Expect anything from diapers featuring motifs of Bluey to super-soft direct-to-consumer brands. There are also eco-friendly disposable diapers for those not interested in reusable options but who want to take Mother Nature into account. These are typically made from 100% plant-based materials and are compostable, says Jay Lovenheim, M.D., a pediatrician in New Jersey. You'll want to decide if the material is important to you. As far as fit goes with different materials, most all diapers fit the same, but you may find certain diapers are softer or smoother, or easier to put on and take off.

• Does your child need hypoallergenic diapers?: Another factor to consider is whether your little one needs a hypoallergenic diaper. “For babies [with] more sensitive skin, a hypoallergenic or pre-moisturized product may better fit their needs,” says Dr. Lovenheim. “It is also best to steer clear of scented diapers if your child’s skin reacts quickly to irritants.” If your child does need a hypoallergenic diaper, look for options that say "hypoallergenic" or "for sensitive skin" on the package. Diapers fit snug, and these types of diapers won't rub or irritate your baby's skin.

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• Are you using it for daytime or nighttime? Different diapers have different absorbance capabilities so you'll want to think about whether the diaper is going to be used for nighttime or longer wear, or daytime. For daytime, you can typically choose a lighter weight, regular diaper, but if you're using it for night time, you may look for those labeled "overnight. “They're great for longer wear because they are more absorbent, which lowers the risk of diaper rash and irritation," says Dr. DeZure. They also tend to fit tighter to prevent excess liquid from escaping, she adds.

  Picking a diaper size for your baby is like finding the perfect pair of jeans: No one size or brand fits everyone, and you have to try it on first.

  - Chandani DeZure, M.D., pediatrician and BabyCenter Medical Advisor

How to choose the right diaper size for your baby

Once you’ve decided the specific types of diapers your child needs, you can focus on what size works for your baby. “Every body and every baby are unique, so the shape of each baby determines what is the right size diaper for the baby,” explains Dr. DeZure.

Here are other factors, according to Dr. DeZure, that can help you determine if your baby's diaper fits correctly:

• The flaps should close at your baby's midline (kind of like a belt!). “If they overlap, it might be too big, or if it doesn't reach the middle, the diaper might be too small,” she shares.
• A caretaker should be able to tuck two fingers into the diaper waist easily. “This helps ensure it's not too tight at the waist,” says Dr. DeZure. “A diaper shouldn't leave marks on the skin. The diaper also shouldn't sag or fall off easily.”
• The diaper should be snug but not too tight or too loose around the thighs. "Check their inner thighs, which are also hotspots for rashes, " she advises, "and make sure they're snug, but not so tight they leave marks." Also, check to make sure the ruffles around the edge of the diaper are out and not tucked in.

To help determine which diaper is best at the time, try a bunch. Start with a small supply of newborn and/or size one diapers from different brands to determine which fits best for your baby’s body, advises Dr. Lovenheim. And don’t get stuck on one brand and size – just as we change clothing brand preferences over time, so do babies with their diapers. Also, as tempting as it is, try not to buy too many diapers in one size in bulk until you know for sure what diaper size your baby is. If you do find yourself with a surplus of diapers, consider posting in a local Facebook group to see if any other families would trade sizes with you. You can also try selling them on Facebook marketplace or donating them to a friend or family in need.

When in doubt, go for a bigger (not a smaller size). “I like to warn all my parents that the size guidelines on diaper packaging are often very inaccurate and can underestimate the true size needed,” adds Dr. Loveheim. “For example, a diaper that is labeled for 8- to 12-pound children is often too small for a child that size. I tell parents to start by using diapers labeled a size above their baby’s actual weight.”

General baby diaper sizing chart

Here is a general diaper size chart, taking in the most popular diaper brands and creating averages around their offerings (see later down below for specific brand sizing info):

• Newborn: up to 10 lbs
• Size 1: 8-14 lb
• Size 2: 12-18 lbs
• Size 3: 16-22 lbs
• Size 4: 22-34 lb
• Size 5: 27+
• Size 6: 35+
• Size 7: 41+

4 signs your baby needs a different size diaper

Wondering if it might be time for a new diaper? Here's are some telltale signs:

• Their diaper is leaking: If your lap or your baby's clothes are wet, you know it’s time to go shopping. Poop blowouts will happen from time to time, even if your child is wearing the right diaper size, but if it’s becoming super-common, then you know the diaper size may be the issue. “If the diaper holds what it’s supposed to and the outer clothes remain clean, then you are doing well,” Dr. Lovenheim notes. “If you are finding that you are always having to change diapers and outfits, or if the diaper is not absorbing immediately, then try the next size up. A slightly larger diaper provides the flexibility of movement, absorbency, and space to contain most loose bowel movements.”
• The flaps don't touch: An easy way to tell that a diaper is too small is if the flaps don’t reach your baby's midline area (around the belly button) when you close them.
• Their bum is out: Check to see if the butt cheeks are visible, notes Dr. DeZure, as everything will be covered in a well-fitting diaper.
• The skin around the diaper is rashy: It’s also important to check your baby’s skin to look for signs of a too-tight diaper. Examine your little one for marks or rashes, the pediatricians confirm. “Look along the thighs, groin, and belly where the diaper presses against the skin,” Dr. Lovenheim says. “If it is too constricting it may cause a frequent rash or redness in that area,” and it's time to size up.

Diaper sizes by brand

No matter what brand or type of diaper you decide on, it's important to remember that they are all slightly different in sizing. Always check the packaging to make sure before you buy! Here are some of the sizing charts from some of the most popular diaper brands:

Huggies

• Preemie: up to 6 lbs
• Newborn: 6-9 lb
• Size 1: 8-14 lb
• Size 2: 12-18 lb
• Size 3: 16-28 lb
• Size 4: 22-37 lb
• Size 5: 27+ lb
• Size 6: 35+ lb

Pampers

• Size 0: up to 10 lbs
• Size 1: 8-14 lbs
• Size 2: 12-18 lbs
• Size 3: 16-28 lbs
• Size 4: 22-37 lbs
• Size 5: 27+ lbs
• Size 6: 35+ lbs
• Size 7: 41+ lbs
• Size 8: 46+ lbs

Honest

• Newborn: up to 10 lbs
• Size 1: 8-14 lbs
• Size 2: 12-18 lbs
• Size 3: 16-28 lbs
• Size 4: 22-37 lbs
• Size 5: 27+ lbs
• Size 6: 35+ lbs
• Size 7: 41+ lbs

Seventh Generation

• Newborn: up to 10 lb
• Size 1: 8-14 lbs
• Size 2: 12-18 lbs
• Size 3: 16-21 lbs
• Size 4: 20-32 lbs
• Size 5: 27-35 lbs
• Size 6: 35+ lbs

Babies grow fast, and it's hard to keep up with bigger sizes of clothes, much less diapers, so don't be too hard on yourself if you wind up with a closet full of too-tight diaper sleeves. Your baby won’t remember it anyway! And I'll be the first one to admit that when researching this piece, it became abundantly clear that my second daughter, a two-and-a-half-year-old, has clearly been wearing a diaper too small thanks to wet morning pajamas and ongoing thigh rashes.