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Newborn vs 0-3 Months Size

When expecting parents prepare for their new baby, one of the many decisions they have to make is what size of clothing to purchase. It might seem like a simple task, but it is not as easy if you don’t know the difference between the sizes, like the one between newborn vs 0-3 months size.

With our guide in hand, buying clothes for your baby doesn’t need to be a stressful experience.

So how can you pick the perfect fit for your newborn?

Check out our comprehensive comparison of newborn vs 0-3 months size to fill your baby closet with clothes tailored for your newborn. From onesies to sleepers, let’s ensure your baby is dressed for success.

Newborn clothesSource: shutterstock.com / Photo Contributor: Natalia Deriabina

Newborn vs 0-3 Months Size: What’s the Difference?

When it comes to baby clothes sizes, the labels are a general indicator of whether the clothes will fit your baby or not.

In our newborn girls clothing boutique, there are different brands available. Before purchasing, we recommend checking the manufacturer's sizing chart to ensure you get suitable clothing.

When filling your shopping cart with our Bitsy Bug Boutique items, you can rely on the following general baby clothes chart.

Size

Weight*

Height*

Newborn

<8 pounds

<19 inches

0-3 months

9-11 pounds

19-23 inches

*Important notice: Sizes can vary between brands.

Baby Clothes Labels Explained

Your number one priority as a parent is keeping your baby safe, comfortable, and happy. Besides feeding, burping, bathing, and diaper changing, a significant factor influencing your baby’s comfort is their clothes.

You don’t want your baby to be fussy because their clothes are tight-fitting or their oversized outfit doesn’t allow them to move freely. Avoiding these unwanted situations can be done if you understand what baby clothes labels mean.

The size tags indicate the baby’s age range which will probably fit in the clothes. Unfortunately, there’s no one-size-fits-all when it comes to choosing baby clothes, as every baby grows at a different rate.

We wish it could be as easy as buying clothes corresponding to your baby’s age. Even if you buy a clothing piece for your baby according to their age, it might be too small or too big.

For instance, if your baby is enjoying your breast milk or drinks that tasty formula, it might outgrow the newborn or 0-3 month sizes sooner than other babies.

Bear in mind that the sizing also varies between companies. Some brands run small, and you will need a bigger size, while others run big, meaning you must go one size down.

Most common baby clothes sizing labels

While you are shopping, you will notice different labels on the clothes. Here are the available baby clothing sizes in ascending order.

  • Preemie (P)
  • Newborn (NB or N)
  • 0-3 months
  • 3-6 months
  • 6-9 months
  • 9-12 months
  • 12-18 months

Deciding on baby clothing sizes might seem like a small detail, but an extremely important one, nonetheless. While the other sizes are easy to understand, the differences between newborn vs 0-3 months size can be confusing.

So how can you know which one to get? One of the easiest ways is to learn more about each size and how they are measured.

 Newborn Baby Clothes SizeSource: shutterstock.com / Photo Contributor: Vimaliss

Newborn Baby Clothes Size

Newborn baby clothes are designed to fit full-term infants weighing between five and eight pounds. Additionally, the baby shouldn’t be bigger than 19 inches.

As a rule of thumb, there is no greater difference than three or four inches between brands.

For example, the Old Navy newborn clothes are for babies up to seven pounds lbs, and 18 inches. On the other hand, Carter’s size charts show that their newborn clothes fit infants between six and nine pounds and lengths from 18 to 21.5 inches.

Some brands don’t offer newborn-sized baby clothes. Instead, their sizing starts at 0-3 months. Before ordering, research the brand and check its size charts.

Other baby clothing brands have preemie, newborn, and 0-3 month sizes. We know the general newborn vs 0-3 months size difference, but who are preemie clothes for?

Again depending on the brand, preemie baby clothes are for infants weighing up to five or six pounds at birth. In short, newborn and 0-3 months clothes are for full-term babies, while preemies are for babies born before their due date or the smallest infants.

How many newborn-size clothes should I have?

So if your baby is of average weight and height, you will most likely need five to seven newborn-sized outfits and four to six sleepsuits and onesies.

During the first few weeks, it is better to do laundry more frequently than to have clothes you will never use. Adjust your laundry schedule, so you can always have a spare outfit for your little one.

Additionally, the number of clothing pieces you should have in the newborn size depends on the season you are welcoming your baby in. While there is no significant difference, winter babies will need extra warm clothes like a jacket and cardigan.

How long will my baby wear a newborn size?

Your baby will wear its first tiny clothes for a short time. Get used to the fact that you will have to go one size up in a blink of an eye.

First of all, how long you will soak up the cuteness of newborn-size clothes depends on the baby’s weight at birth.

Secondly, the baby’s legs and torso length can determine how long they will wear their newborn clothes. Typically, term babies are born 20 inches, but if your baby has long legs, it might ditch the newborn-sized clothes faster than other babies.

Ultimately, a crucial factor is the baby’s development once you bring them home from the hospital.

More often than not, average infants wear newborn sizes up to eight weeks after birth. There is no universal rule.

You can use the following information as a guide on when your baby will outgrow its newborn-sized clothes.

Baby weight at birth

Newborn size will fit for

5 pounds

8 to 10 weeks

6 pounds

8 weeks

7 pounds

4 to 6 weeks

8 pounds

2 to 3 weeks


Some babies are born nine pounds or above, meaning they will directly start with a size designed for 0-3 months babies. Don’t be alarmed; it is perfectly healthy.

If you are packing your hospital bag, we recommend throwing newborn and 0-3 months size clothes. You can also use ultrasound weight estimates to purchase the accurate size.

0-3 Months Baby Clothes Size

You should get 0-3 months’ clothes if your baby is between nine and 11 pounds and approximately 19 to 23 inches tall.

As for the newborn sizes, different brands size and label things differently. Hence, use different sizing charts for 0-3 months baby clothes.

Old Navy clothes labeled 0-3 months are for little ones between seven and 12 pounds and 19 and 23 inches.

However, Carter’s and OshKosh clothes from 0-3 months are suitable for babies weighing nine to 12.5 pounds. The length of the clothes is perfect for infants between 21.5 and 24 inches.

0-3 Months Baby Clothes Size
Source: shutterstock.com / Photo Contributor: Netrun78

Is 0-3 month clothing for newborns?

An average full-term baby is born 20 inches long, meaning it will be perfectly okay to dress your newborn in 0-3 months clothing. The only issue is that if the brand runs big, it might be a little baggy for them.

Since babies up to one year grow really fast, the 0-3 months clothes will fit them perfectly in two or three weeks. Sometimes even faster. Rolling up their sleeves will do the trick just fine until that time comes.

How long will my baby wear 0-3 months size?

As the size itself suggests, the 0-3 months size fits babies up to three months of age.

Friendly tip: If your baby is three months old, avoid buying 0-3 months' clothes. Instead, opt for the three to six months sizes.

How many 0-3 months clothes should I have?

Compared to the newborn size, your child will wear the 0-3 months clothes longer. Hence, you need more clothes of this size.

Many parents prefer having two outfits in hand each day of the week, meaning you will need fourteen individual outfits. You can mix and match different types of pants, tops, or onesies.

Furthermore, you will need at least 10 sleepsuits. There will be a lot of diaper leaks, so having a spare sleepsuit or pajama set is a must. From zip-ups, snaps, and buttons to irresistible designs, you will have a lot of options to choose from.

In addition to the size and design, you must pick comfortable and durable materials. Our suggestion is to choose cotton. It is guaranteed it will keep your baby happy and cozy.

Baby essentials for the first three months

As you prepare for the arrival of your little one, you might face difficulties finding clothing items. It is easy to get lost in the sea of adorable baby options.

In the beginning, it is important to focus on buying the essentials. Avoid overbuying. The closet of your newborn should have the following clothes:

  • Onesies
  • Sleepsuits or pajamas
  • Short and long-sleeved bodysuits
  • Tops - t-shirts, sweaters, and cardigans
  • Bottoms: leggings, jeans, and footed pants
  • Hats
  • Mittens
  • Socks
  • Dressy outfits
  • Blankets
  • Swaddlers
  • Light jacket
  • Shoes
  • Drool bibs

This list features only the essentials. You can additionally get things like scarves, swimsuits, sun hats, wearable blankets, and much more.

Frequently Asked Questions

What size does a newborn fit?

Newborn sizes are generally designed for babies born at eight or fewer pounds. Clothes labeled for newborns are usually designed for babies up to 19 inches. Note that there might be small adjustments to the sizes between different brands.

What size is a 0-3 month baby?

Typically, the baby clothing size from 0 to 3 months is an accurate fit for a baby weighing from nine to 11 pounds. Regarding the baby’s height, 0-3 month clothing fits munchkins between 19 and 23 inches.

Is it better to buy a newborn or 0-3 clothes?

It depends on your preferences and how big your baby will be at birth. If you want extra wear out of the clothes, buy 0-3 months. On the contrary, if you want clothes to fit your baby just right, buy newborn-size clothes assuming your baby weighs less than eight pounds. 

Is 0-3 months the same as three months in baby clothes?

Generally, yes. The 0-3 month clothes are the same size as clothes labeled only with three months or 3M. Both sizes mean that they fit babies up to 3 months of age.

Exceptions are some brands where 0-3 months and three months of clothing differ. The 0-3 months are more defined to the baby's body, while the 3-month clothes have longer sleeves and legs.

Newborn vs 0-3 Months Size: Which Is the Perfect Fit for My Baby?

It’s more than clear that the design is a personal preference. However, you must pick the right size. Many parents ask whether they should buy a newborn or a 0-3 months size for their newest and sweetest family member.

Unfortunately, there is no one-size-fits-all answer. The perfect fit depends on the baby’s size at birth and development. Hence, you should use your baby's height and weight as a guide for buying clothes.

The best way to solve the newborn vs 0-3 months size dilemma is to buy a few newborn-sized clothes and get more pieces of the 0-3 months size. This way, you will cut down on your expenses and shopping trips when your baby outgrows the newborn size in the first couple of weeks.

Lastly, pay attention to the clothes material, as some materials are prone to shrinking when washed. If you have an eye on materials like pure cotton, buy big because you will likely take it out of the washer a tad smaller.

Sam Milam

Sam Milam, author

Sam Milam is a freelance writer, photographer, and yoga teacher. She is passionate about educating herself and others about attachment parenting, social justice, and living an authentic, empowered life. When she isn't working, she can be found exploring the Pacific Northwest with her two kids. Sam is a regular contributor for Washington Post, POPSUGAR, USA Today, Parent Map, and Gronk Nation.

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