As a new mom or dad, chances are, you’ll have that moment where you stare overwhelmed at the diaper aisle, wondering, “Size 1, Size 2, Size 3… What does this even mean? Will this fit my baby? How many should I even buy?” That’s why we developed this diaper size guide!
In this baby diaper size guide, we’ll help you understand how diaper sizing works, how to pick the right one for your baby, and how to avoid wasting money on sizes that won’t fit. We’ve all been there, and you’ll soon be a diaper-sizing expert.
Understanding Diaper Sizes
How Do Diaper Sizes Work?
Labels like “1”, “2”, and so on, represent the diaper size, which corresponds to the baby’s weight range the diaper is meant to fit.
A Size 1 diaper, for example, is for babies weighing 8-14 lbs, while a Size 2 caters to babies weighing 12-18 lbs. As size increases, the weight range does as well. Later on, you’ll get to know the specific weight ranges for each diaper size.
Typically, sizing starts with Newborns or “N”, and thus, are the smallest-sized diapers. Sizes 1, 2, and so on, follow, typically ending at Size 8.
There are also preemie diapers represented as “P”, which is meant for smaller premature babies that weigh less than 6 lb.
Two of the most popular brands, Pampers and Huggies, follow this sizing and weight guidelines, although, each may fit your baby differently (but more on that later).
On a related note, a common question we get is, why isn’t age considered the main factor for diaper size?
It’s worked for toys, baby bottles, and clothes, so why not diapers?
Unlike toys and feeding products, which are tied to developmental milestones, diaper sizing is more about practicality…
Babies grow at different rates, and their weight and body shape vary widely even within the same age group. A 4-month-old could be wearing a size 3 diaper because of a rapid growth stage, while another baby of the same age might still fit comfortably in size 2.
That’s why you don’t often see diaper brands using age ranges in their sizing guides. Well, a few might, but it’s pretty rare.
Key Factors in Choosing the Right Size
Weight
When choosing a diaper size, consider weight as the primary measurement for determining the right size. So, if your baby weighs, say, 20 lbs, you’ll want to choose Size 3 diapers, which are suited for babies between 16 to 28 lbs.
To know your baby’s weight, simply use a home baby scale or check it during one of their well-baby visits.
Now, we’ve made it clear from the start why weight should always come first. But why is that the case?
It’s not just because we instinctively think that weight affects fit (the heavier the baby, the more likely they are to have bigger arms or a wider waist.). It has more to do with weight being an indicator of the volume of pee or poop your baby can produce.
A 20-pound baby would generally have more pee or poop than a 10-pound baby. So, if you’re using Size 1 instead of Size 3, you’re putting your baby in a diaper with less absorbency level – meaning a leak is much more likely to happen.
Body Shape and Fit
Babies with chubby legs or a fuller belly might need a diaper that’s a little roomier, while babies with slimmer waists might be more comfortable with a snugger fit.
This is one reason why, if you look at the diaper sizing guide, you’ll notice an overlap in weight ranges. For example, Size 3 diapers accommodate weights between 16 and 28 lbs, while Size 4 diapers suit babies weighing 22 to 37 lbs – an overlap between 22 and 28 lbs.
So, if your baby’s weight falls between the two sizes, whether you settle with a Size 3 or 4 comes down to your baby’s body shape, and thus, the fit that works best for them.
Here are some visual cues that will help you evaluate whether or not a diaper size properly fits your baby:
- The diaper covers your baby’s bottom fully.
- The diaper leaves no gaps around the leg cuffs.
- The diaper is snug around the waist, right below the belly button, without the tabs stretching too much.
Diapers that come with adjustable tabs should allow you to customize the fit around your baby’s waist and legs.
Also, if two fingers comfortably fit under the waistband, that should indicate a good fit.
Age
Age should be used only as a secondary guide for choosing diaper size.
And that’s because some babies grow quickly and need to move up in size earlier than others, while others stay in a smaller size for longer. This means you’ll eventually go back to looking at weight and fit to know the best option for your baby.
Earlier, we mentioned how some brands may have age-based sizing charts alongside weight ranges. That is to help new parents – especially those who aren’t sure of their baby’s weight yet – make quick decisions about which diaper size to choose.
Diaper Size Guide: Charts by Popular Brands
We’ve taken the two reliable diaper brands – Pampers and Huggies – and laid out both brands’ baby diaper chart for size-based fitting for different weights below.
Pampers Diaper Size Chart
| Pampers Diaper Size | Weight (lbs) | Average No. of Diapers Per Day | Duration in Size (in Months) |
| Size P1 diapers | <6 lbs | as needed | as needed |
| Size N diapers | <10 | up to 10 | 1.6 |
| Size 1 diapers | 8-14 lbs | up to 9 | 1.7 |
| Size 2 diapers | 12-18 lbs | up to 8 | 2.8 |
| Size 3 diapers | 16-28 lbs | up to 7 | 5.8 |
| Size 4 diapers | 22-37 lbs | up to 7 | 6.8 |
| Size 5 diapers | 27+ lbs | up to 6 | 5.0 |
| Size 6 diapers | 35+ lbs | up to 6 | 5.8 |
| Size 7 diapers | 41+ lbs | up to 6 | 4.1 |
| Size 8 diapers | 46+ lbs | varies | – |
Huggies Diaper Size Chart
| Huggies Diaper Size | Weight (lbs) | Average No. of Diapers Per Day | Duration in Size (in Months) |
| Size P diapers | Up to 6 lbs. | As needed | Varies |
| Size N diapers | Up to 10 lbs. | 8 per day | 1 month |
| Size 1 diapers | 8-14 lbs. | 6 per day | 1.5 month |
| Size 2 diapers | 12-18 lbs. | 5 per day | 3 month |
| Size 3 diapers | 16-28 lbs. | 5 per day | 7 month |
| Size 4 diapers | 22-37 lbs. | 4 per day | 8 month |
| Size 5 diapers | >27 lbs. | 4 per day | 6 month |
| Size 6 diapers | >35 lbs. | 4 per day | 3.5 month |
| Size 7 diapers | >41 lbs. | Varies | Varies |
| Size 8 diapers | >46 lbs. | Varies | Varies |
Comparing Pampers vs. Huggies Diaper Sizes
Looking at the size and weight chart guides earlier, both Pampers and Huggies offer similar weight ranges for their diaper sizes. So, it’s safe to say that their differences go beyond just sizing and more about how they fit and the unique technology each brand uses.
Fit can vary a lot from baby to baby. In fact, many parents say that, for the same size, Pampers tend to run longer and deeper, making them great for taller babies, while Huggies often fit better for babies with wider waists and bottoms.
That said, parents may choose one brand over the other simply because it fits their babies better – period.
Diaper technology, on the other hand, is a different story.
It says a lot about how a diaper is designed and made, which affects the diaper’s comfort, flexibility, and absorbency.
Pampers Swaddlers, for instance, is built with a Wetness Indicator to signal when a change is needed, whereas the Pampers Baby-Dry is equipped with the LockAway Channels™, which help to absorb wetness and lock it away from the skin for up to 12 hours.
For Huggies, the Huggies Little Movers, tailored for active babies, feature a curved shape and Double Grip Strips™ to prevent sagging during movement, while the Huggies Little Snugglers is built with GentleAbsorb® Liner that absorbs wetness on contact and provides a soft fit for delicate skin.
When to Change Diaper Sizes
Signs the Diaper is Too Small
It’s not always obvious when a diaper is too small. Here are the signs that should tell you it’s time for your baby to get in a much bigger diaper size:
- If you have to stretch tabs too far towards the center of the waistband to fasten them
- If you can’t comfortably fit two fingers under the waistband
- If you have to force the diaper all the way up to fully cover your baby’s bottom
- If you see red marks anywhere on your baby’ waistline or thighs
- If your baby has frequent diaper rash (probably due to frequent leaks or blowouts)
- If your baby seems uncomfortable and tries to pull down the diaper during diaper changes
Age and Weight Milestones for Diaper Changes
As your baby grows, their diaper needs will change. Below is a helpful guide you can use as a benchmark for when to move up a diaper size. The weights listed are based on the 50th percentile for both boys and girls.
| Baby age | Female(50th percentile) Weight and Diaper Size | Male(50th percentile) Weight and Diaper Size |
| Birth | 7 lb (N) | 7 lb (N) |
| 1 month | 9 lb (Size 1) | 9 lb (Size 1) |
| 2 months | 11 lb (Size 1) | 12 lb (Size 2) |
| 3 months | 12 lb (Size 2) | 14 lb (Size 2) |
| 4 months | 14 lb (Size 2) | 15 lb (Size 2) |
| 5 months | 15 lb (Size 2) | 16 lb (Size 3) |
| 6 months | 16 lb (Size 3) | 17 lb (Size 3) |
| 7 months | 16 lb (Size 3) | 18 lb (Size 3) |
| 8 months | 17 lb (Size 3) | 18 lb (Size 3) |
| 9 months | 18 lb (Size 3) | 19 lb (Size 3) |
| 10 months | 18 lb (Size 3) | 20 lb (Size 3) |
| 11 months | 19 lb (Size 3) | 20 lb (Size 3) |
| 12 months | 19 lb (Size 3) | 21 lb (Size 3) |
Again, these are not hard rules. Some babies stick to a size for months, while others outgrow them in weeks. For much older babies, diaper changes can be less predictable due to growth spurts.
When we talk about milestones, we should also look at developmental milestones, which speak a lot about your baby’s overall activity.
For example, once your baby is ready for potty training (which can happen as early as 18 months), you may want to adjust and consider the more lightweight pull-ups, which allow your baby to move more freely and are easier to change.
How to Avoid Overbuying the Wrong Size
It’s tempting to stockpile diapers, especially when you see a sale. But beyond the savings, it can feel reassuring to have a stockpile ready just in case.
However, remember that babies grow fast, and overbuying could leave you with a stash of diapers you can’t use.
The best approach is to buy smaller quantities of each size.
Start by following diaper size charts, paying attention first to the recommended estimates for the average number of diapers per day.
For example, for Size 1 diapers, you would be using about 9 of them per day. That means you’ll need 63 diapers in a week, and about 270 diapers in a month.
If your baby is a bit older, you might have a better sense of their growth rate, which can help you plan how many diapers to buy and how long each size can last. But again, you never know when growth spurts will hit.
The first approach is much more conservative, and we recommend that you stick by it so that you’re less likely to end up with diapers that won’t fit your baby.
Special Considerations for Newborn Diapers
Newborn Diaper Size Guide
Newborn diapers are specifically designed for babies who weigh up to 10 lbs. These are smaller than Size 1 diapers, which range from 8 to 14 lbs. If your baby is born prematurely, you may need to use preemie diapers, which are specially designed for babies weighing less than 6 lbs.
Here’s a look at the newborn diapers size chart:
| Diaper Size | Weight (lbs) |
| Preemie diapers | < 6 lbs |
| Newborn “N” diapers | < 10 lbs |
| Size 1 diapers | 8-14 lbs |
With preemie and newborn diapers being smaller, you can expect them to have snugger leg cuffs, which offer additional support to prevent leaks.
Another major feature you can expect is the umbilical cord cutout at the front, which helps prevent irritation in the umbilical cord stump area and allows it to heal properly. Size 1 diapers typically don’t have this cutout, as babies using them have usually outgrown the need for it.
Choosing the Best Diaper for Newborns
When looking for the best diaper for your newborn, make sure to consider things such as:
- Umbilical Cord Cutout. Newborn diapers, like Pampers Swaddlers, have umbilical cord cutouts, which help prevent irritation around the belly button.
- Wetness Indicator. A wetness indicator is a strip that changes color when the diaper is wet, letting you know it’s time for a change without having to guess.
- Softness and Breathability. Newborns have sensitive skin, so you’ll want a stretchy and flexible diaper made with ultra-soft, breathable material to prevent irritation and keep their skin comfortable.
- Extra Absorbency. Newborns tend to urinate more often in small amounts. Diapers, such as Huggies Special Delivery diapers, are highly absorbent, durable, and leak-proof, effectively wicking away moisture quickly to keep your baby dry and prevent diaper rash.
Remember, every baby is different, and what works for one might not work for another.
You can start by purchasing sample packs or buying smaller quantities. This way, you can test out different brands and features to see which diaper fits your baby best without committing to a full box.
Frequently Asked Questions About Diaper Sizing
How Many Diapers Do I Need for Each Size?
The number of diapers you’ll need depends primarily on your baby’s weight. Newborns usually go through about 10 diapers a day, while babies in Size 3 diapers (around 5 to 6 months old) might need closer to 5 diapers daily.
To estimate your needs, check the diaper size chart from your chosen brand. These charts have guidelines, including the average number of diapers used per day and how long your baby is likely to stay in each size.
When Should I Switch Diaper Sizes?
You should switch baby diaper sizes when the diaper is either too small or too big for your baby.
If the diaper is too small, you might notice red marks on the skin, frequent leaks or blowouts, diaper rash, or extra fussiness during changes.
On the other hand, a diaper that’s too big or loose won’t stay in place properly and will likely have gaps around the leg cuffs, which can lead to leaks and blowouts too.
What If the Diaper Seems Too Loose?
If the diaper seems too loose, chances are, it won’t effectively protect your baby against leaks or blowouts, which can cause diaper rash, skin irritation, and other discomforts.
A well-fitting diaper should have tabs that reach the center of the waistband to ensure a snug and secure fit around the waist and thighs.