Diaper Sizes by Age Guide: Diaper Size and Weight Chart

Most new parents assume diaper sizes align with age, much like baby clothes. But here is the reality check: most brands size strictly by weight. Every baby has a different shape, and getting that fit right is the only thing standing between you and a messy blowout.

You cannot try diapers on in the aisle, and trial-and-error gets expensive. To save you money and laundry loads, we broke down the size charts for every major brand. Whether you need disposables, cloth, or swim options, here is how to find the perfect fit.

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Diaper Sizes By Age and Weight

If you do not have a preferred brand yet, this table provides a general baseline. Remember, this is just an estimate. Your baby’s body shape (chunky thighs vs. long torso) plays a huge role in fit.

Diaper Size	Avg. Age	Weight Range
N	Newborn to 4 weeks	Up to 10 lbs
1	2 to 4 months	8 to 14 lbs
2	4 to 7 months	12 to 18 lbs
3	7 to 12 months	16 to 28 lbs
4	18 to 48 months	22 to 37 lbs
5	3 years+	27 lbs+
6	4 years+	35 lbs+

Disposable Diaper Sizes

Disposable diapers remain the top choice for convenience. However, sizing isn’t universal across brands. A Size 1 in Huggies might fit differently than a Size 1 in Pampers.

Here are the specific weight charts for the most popular disposable brands.

Pampers Swaddlers Size Chart

Pampers Swaddlers are a hospital favorite for a reason. They are incredibly soft and feature a “blowout barrier” at the back waist to prevent messes. The newborn size includes a notch for the umbilical cord, while larger sizes feature wetness indicators to help you know when it is time for a change.

Weight	Size
Up to 6 lbs	Preemie
Up to 10 lbs	Newborn
8 to 14 lbs	Size 1
12 to 18 lbs	Size 2
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Huggies Little Movers Size Chart

Once your baby starts crawling and walking, fit becomes critical. Huggies Little Movers are designed for active babies. They feature a contoured shape and “Double Grip Strips” that hold the diaper in place during vigorous play. They also include a SizeUp indicator, which lets you know exactly when the current fit is becoming too tight.

Weight	Size
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Mama Bear Size Chart

Mama Bear is Amazon’s private-label brand, offering a budget-friendly alternative to the big names. They provide solid leakage protection and use hypoallergenic materials. If you go through diapers quickly and want to save money without sacrificing quality, these are a strong contender.

Weight	Size
Up to 10 lbs	Newborn
8 to 14 lbs	Size 1
12 to 18 lbs	Size 2
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Pampers Pure Size Chart

If you prioritize natural materials, Pampers Pure is a great hybrid option. They offer the trusted Pampers leak protection but are free from chlorine bleaching, fragrance, and parabens. The cotton-enhanced outer cover makes them softer than standard plastic-backed diapers.

Weight	Size
Up to 10 lbs	Newborn
8 to 14 lbs	Size 1
12 to 18 lbs	Size 2
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Luvs Ultra Leakguards Size Chart

Luvs markets itself to experienced parents who want performance without the high price tag. Their “Nightlock” technology makes them surprisingly absorbent for the price point. The tabs are large and stretchy, making it easy to get a secure fit on wiggly babies.

Weight	Size
Up to 10 lbs	Newborn
8 to 14 lbs	Size 1
12 to 18 lbs	Size 2
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Huggies Snug & Dry Size Chart

Huggies Snug & Dry focuses purely on absorption speed. They claim to absorb wetness in under ten seconds, which helps prevent diaper rash. If your baby is a heavy wetter and you need a reliable daily workhorse diaper, these are an excellent choice.

Weight	Size
Up to 10 lbs	Newborn
8 to 14 lbs	Size 1
12 to 18 lbs	Size 2
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Honest Diapers Size Chart

The Honest Company is famous for its adorable, Instagram-worthy prints. Beyond the aesthetics, they are legitimate eco-friendly contenders. They use plant-based materials and hold a surprising amount of fluid. If you want style and sustainability, this is your brand.

Weight	Size
8 to 14 lbs	Size 1
12 to 18 lbs	Size 2
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Bambo Nature Size Chart

Bambo Nature is often considered the gold standard for eco-friendly disposable diapers. They are thin, breathable, and free of harmful chemicals. While they are pricier than average, parents of children with eczema or extremely sensitive skin swear by them.

Weight	Size
4 to 8 lbs	Newborn 1
6 to 13 lbs	Mini 2
11 to 19 lbs	Midi 3
15 to 39 lbs	Maxi 4
26 to 48 lbs	Junior 5
35 to 66 lbs	XL 6

Pampers Cruisers Size Chart

Cruisers are the next step up from Swaddlers. They are designed specifically for toddlers on the move. The “3-Way Fit” adapts at the waist, legs, and bottom to ensure the diaper doesn’t gap when your child runs or climbs.

Weight	Size
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6
41 lbs+	Size 7

Huggies Little Snugglers Size Chart

Little Snugglers are the direct competitor to Pampers Swaddlers. They focus heavily on skin health, featuring a breathable outer cover and a liner that pulls mess away from the skin. The pocketed back waistband is excellent for containing runny newborn poop.

Weight	Size
1 to 5 lbs	Preemie
6 to 9 lbs	Newborn
8 to 14 lbs	Size 1
12 to 18 lbs	Size 2
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Overnight Diaper Sizes

Standard daytime diapers are often not enough for 12 hours of sleep. If you are waking up to wet sheets, you need extra absorbent polymers.

Below are size guides for dedicated overnight diapers and bedtime underwear.

Huggies Overnites Size Chart

Huggies Overnites are the best-selling night diaper for a reason. They offer up to 12 hours of protection and feature double leak guards around the legs. The SnugFit waistband helps prevent leaks even if your baby tosses and turns all night.

Weight	Size
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

GoodNites Bedtime Underwear Size Chart

For older children dealing with bedwetting, baby diapers won’t fit. GoodNites are discreet bedtime underwear designed for larger kids. They absorb odors and offer 40% more protection than training pants.

Weight	Size
28 to 45 lbs	XS
38 to 65 lbs	S to M
60 to 120 lbs	L to XL

Honest Overnights Size Chart

Honest Overnights take their standard eco-friendly design and boost the absorbency by 20%. They maintain a thin profile, so it doesn’t feel like your baby is wearing a bulky pillow. The sleep-themed sheep designs are a cute bonus.

Weight	Size
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Pampers Ninjamas Size Chart

Ninjamas are Pampers’ answer to GoodNites. They are designed to be “stealthy” so older kids don’t feel embarrassed wearing them. The LockAway channels absorb high volumes of liquid instantly. They look and feel like real underwear, which is great for your child’s confidence.

Weight	Size
38 to 70 lbs	S to M
64 to 95+ lbs	L to XL

Seventh Generation Overnight Size Guide

If you want a high-capacity core without the chlorine processing, Seventh Generation Overnights are the way to go. They use FSC-certified wood pulp for absorption. The package is clearly marked with “Sylvia the Sheep” so you don’t accidentally grab a daytime diaper at bedtime.

Weight	Size
22 to 32 lbs	Size 4
27 to 35 lbs	Size 5
35 lbs+	Size 6

Swim Diaper Sizes

Standard diapers swell up like a balloon in the pool. Swim diapers are designed to hold solids *only*. Do not put these on your baby until you are at the poolside, because they will not hold pee.

Alvababy Swim Diapers Size Chart

These reusable swim diapers save money and reduce waste. They use a system of snaps to adjust the height and waist, meaning one diaper can last you through several growth spurts. They are strictly for containing poop, so they are lightweight and perfect for the beach.

Weight	Size
10 to 40 lbs	S
18 to 55 lbs	L

Huggies Little Swimmers Size Chart

Little Swimmers are the most popular disposable option. They feature tear-away sides, which is a lifesaver when you need to change a wet, slippery baby. The material does not expand in water, ensuring your baby can kick and swim freely.

Weight	Size
16 to 26 lbs	Size 3
24 to 34 lbs	Size 4
32 lbs+	Size 5 to 6

Pampers Splashers Swim Diapers Size Chart

Pampers Splashers have a 360-degree stretchy waistband that pulls on like underwear. This provides a gap-free fit for active water play. They also include “Easy-Tear” sides for quick removal. The graphics look like real swim trunks, which is a nice touch.

Weight	Size
13 to 24 lbs	S
20 to 33 lbs	M
31 to 40 lbs	L

Langsprit Swim Diaper Size Chart

Langsprit offers a durable reusable option made with polyurethane laminate (PUL). This fabric is waterproof and tough enough to withstand concrete pool decks and sand. The adjustable snaps allow you to customize the leg openings for a tight seal against accidents.

Weight	Size
10 to 19 lbs	Size S
20 to 40 lbs	Size L

Cloth Diaper Sizes

Cloth diapers have made a huge comeback due to their environmental benefits and cost savings over time. While “One-Size” options are popular, many brands still offer sized systems for better fit.

Kanga Care Lil Joey Size Chart

The Lil Joey is designed specifically for newborns and preemies. Most “one-size” cloth diapers are too bulky for a brand new baby. These feature an umbilical cord snap-down and dual inner gussets to contain those explosive newborn messes.

Weight	Size
4 to 12 lbs	Size newborn

Rumparooz Diaper Cover Size Chart

This is a waterproof cover designed to go over fitted diapers or prefolds. Since it doesn’t have absorbent cloth attached, you can often wipe it clean and reuse it multiple times between washes. The “One Size” option grows with your baby using snap risers.

Weight	Size
4 to 15 lbs	Preemie/newborn
6 to 35 lbs+	One size

OsoCozy Prefolds Size Chart

Prefolds are the classic cloth diaper. They are rectangular pieces of cotton gauze that you fold and secure with a cover. OsoCozy uses unbleached Indian cotton which is incredibly durable. You must wash them a few times before use to “prep” them for maximum absorbency.

Weight	Size
7 to 15 lbs	Infant size 1
15 to 30 lbs	Infant size 2

Rumparooz Pocket Diaper Size Chart

Pocket diapers have a waterproof shell with a pocket inside where you stuff an absorbent insert. This allows you to customize the absorbency level. Rumparooz are famous for their “6r Soaker” system and double leg gussets that lock messes inside.

Weight	Size
6 to 40 lbs+	One size

GroVia Reusable Hybrid Size Chart

GroVia Hybrids offer flexibility. You use a single shell and snap in either a cloth soaker pad or a disposable bio-soaker. This makes them great for daycare or travel. The shell uses hook-and-loop (velcro style) or snaps to fit a wide range of babies.

Weight	Size
8 to 30 lbs	One size

Alvababy Pocket Diapers Size Chart

Alvababy is the go-to brand for building a stash on a budget. They are pocket diapers that come with microfiber inserts. The inner lining is a “stay-dry” suede cloth that wicks moisture away from the skin. The vast array of snap adjustments makes them a true one-size-fits-all solution.

Weight	Size
6.6 to 33 lbs	One size

Pull-On Diaper Sizes

Pull-on diapers (or training pants) are essential for potty training. They allow toddlers to pull them up and down like underwear, fostering independence.

Eco by Naty Size Chart

Eco by Naty pull-ups are a clean, plant-based option. They are certified vegan and contain 0% plastic on the skin. If you are potty training a child with sensitive skin, these are a safe bet. The sides tear away easily for those inevitable accidents.

Weight	Size
18 to 33 lbs	Size 4
26 to 40 lbs	Size 5
35 lbs+	Size 6

Huggies Little Movers Slip-On Size Chart

Note that these are distinct from “Pull-Ups.” These are standard diapers designed to slip on for standing changes. If your baby refuses to lie down for a diaper change but isn’t ready to potty train, these are the solution. They have the absorbency of a diaper but the fit of pants.

Weight	Size
16 to 28 lbs	Size 3
22 to 37 lbs	Size 4
27 lbs+	Size 5
35 lbs+	Size 6

Bambo Nature Training Pants Size Chart

Bambo Nature’s training pants maintain their eco-standards with a breathable, flexible design. They are dermatologically tested and super soft. The elastic waist is forgiving, making it easy for toddlers with limited motor skills to handle them alone.

Weight	Size
15 to 31 lbs	Size 4
27 to 40 lbs	Size 5
40 lbs+	Size 6

Huggies Pull-Ups Training Pants Size Chart

Huggies Pull-Ups are the market leader for a reason. They feature fading graphics (Mickey/Minnie) that disappear when wet, giving kids a visual cue to learn. They also have refastenable sides, so you can check for mess without taking the whole pant off.

Weight	Size
16 to 34 lbs	2T to 3T
32 to 40 lbs	3T to 4T
38 to 50 lbs	4T to 5T
46 lbs+	5T to 6T

Pampers Easy Ups Size Chart

Pampers Easy Ups feel more like cotton underwear than any other brand. They have a 360-degree stretchy waistband and don’t have the “crinkly” sound of diapers. While they don’t have refastenable sides (you have to rip them to remove), they are highly absorbent for naps and travel.

Weight	Size
16 to 34 lbs	2T to 3T
30 to 40 lbs	3T to 4T
37 lbs+	4T to 5T

5 Tips for Sizing Diapers Correctly

If you are dealing with leaks, the diaper size is usually the culprit. As a first-time mom, I learned the hard way that weight ranges are just suggestions. Here are the real signs you need to size up:

• Frequent Leaks: If your baby leaks more than once a week, the diaper is likely too small to hold the volume of waste. It could also mean the rise is too short, leading to leaks up the back.
• Red Marks: Check your baby’s thighs and waist during a change. Deep red indentations from the elastic mean the diaper is cutting into their skin. It should fit snugly, but not tight.
• The “Gap” Test: You should be able to fit two fingers comfortably under the waistband. If you have to struggle to pull the tabs closed, or if they are fastening at the very edge of the strip, move up a size.
• Butt Coverage: The diaper should fully cover your baby’s bottom. If it looks like a “bikini cut” or shifts to the side constantly, it is too small.
• Try Different Brands: Just because your baby is a Size 2 in Huggies doesn’t mean they are a Size 2 in Pampers. Buy small packs when switching brands to test the fit before committing to a giant box.

FAQs

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In Conclusion

Finding the right diaper size feels like a moving target because babies grow overnight. Do not stress if you have a few leaks along the way; it is a rite of passage for every parent. Trust the weight charts, but trust your eyes more. If it looks tight, size up. Good luck!