four infant boys sitting together wearing one-piece bodysuits

How to Buy the Right Size for Your Baby

By: Brooke Hamilton

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As any parent knows, understanding what size clothes to buy for your baby can be a tricky task. Babies grow at an astonishing rate, so finding clothing that fits while still allowing room for growth is crucial. On top of that, baby sizes are different from adult sizes, adding an extra layer of challenge to the process of curating your baby’s wardrobe.


One common dilemma parents face is choosing between 2T vs. 24 months sizes, as both options cater to toddlers but have slight differences in fit. This makes it even more important to carefully consider your baby’s current growth stage when selecting clothes.


Fortunately, we’re pros at baby clothes and baby clothes sizes.


Learn more about how important it is to choose the right size, how to decode size labels, and tips for accurately measuring your little one.

Why Choosing the Right Size is Important

Selecting the right clothing size for your baby is more than just a matter of style—it's essential for their comfort and development.


First and foremost, babies have delicate skin that can easily be irritated by tight or ill-fitting clothes. The right size ensures that there are no pressure points, allowing your baby to move freely and explore their world without restriction.1


This freedom of movement is also vital for the development of their motor skills, helping them stretch, crawl, and grab with ease.

two infants lying next to one another on top of blanket

Understanding Baby Clothing Sizes

With a better understanding of the importance of properly sized baby clothes, let's delve into the essentials of sizing to make shopping for your little one a seamless and enjoyable experience.

Decoding Size Labels: Newborn, 0-3 Months, And Beyond

When you first start shopping for baby clothes, you'll notice a variety of size labels, such as "Newborn," "0-3 Months," "3-6 Months," and beyond. These labels generally correspond to the age range for which the clothing is designed, but they’re more of a guideline than a strict rule.2


What do we mean by this?


Newborn clothing typically fits babies weighing up to about 7 pounds, but every baby is unique. Some babies outgrow newborn clothes almost instantly, while others linger in them for weeks. Meanwhile, the "0-3 Months" baby clothes size is meant to accommodate infants up to about 12 pounds, providing a little more room to grow.


The key is to consider the baby's weight and length as much as their age, ensuring the clothes provide comfort and ease of movement, whether you're building a baby capsule wardrobe or stocking up on seasonal essentials.

close up of boys button up shirt with motorcyle print

How Baby Sizes Vary by Brand

It's important to note that baby clothing sizes can vary significantly from one baby clothing brand to another. At Posh Peanut, we strive to provide consistent sizing and detailed size charts to help guide your selection.


However, other brands might have different standards, meaning a "3-6 Months" size from our collection might fit differently than another. So, if you’re wondering how to size baby clothes, it’s important to remember that some brands cater to a snug fit, while others provide a more generous cut.


When shopping online, always check size charts and reviews to gauge how a brand's clothes might fit your baby. If you're in doubt, it's often wise to size up, allowing your baby room to grow into the clothes comfortably.

Factors Influencing Baby Size: Weight vs. Height

Understanding what influences your baby’s clothing size can further simplify your shopping experience. While age is a common reference point, weight and height are more accurate indicators of the appropriate size.


Keep in mind that babies grow at their own pace, and their proportions can vary widely. For example, a long and lean baby might need a larger size for length, even if their weight is within a smaller size range. Alternatively, a shorter baby with a healthy weight might fit better in a size that's typically meant for a younger age group.


We recommend measuring your baby’s height and weight and comparing it with our size chart to ensure the best fit.

toddler boy standing up wearing nature themed top and black joggers

Tips for Accurately Measuring Your Baby

Accurately measuring your baby is essential to finding perfectly sized clothing. Follow these practical tips to help you get precise measurements:


  • Choose the right time – Measure your baby when they’re calm and content. After a nap or feeding is ideal, as they’re more likely to be relaxed.


  • Use a soft measuring tape – A soft measuring tape is gentle on your baby's delicate skin and will provide more accurate results.


  • Measure twice – Double-check measurements to ensure accuracy.


Pro tip: When measuring for clothing, remember that diapers add bulk. Consider this when taking waist and hip measurements.

How to Measure Your Baby’s Height and Weight

Not quite sure how to measure your baby’s height and weight? Here’s our advice:


  • Height – Lay your baby on a flat surface and gently stretch their legs. Use a soft measuring tape to measure from the top of their head to the bottom of their heels. Mark the spot where their head starts and their feet end, and then measure the distance between the marks.


  • Weight – If available, use a baby scale. Alternatively, weigh yourself first, then weigh yourself holding your baby, and subtract your weight from the combined weight to get your baby’s weight.

When to Measure for Seasonal Clothes

Seasonal changes require a wardrobe update to keep your baby comfortable in varying temperatures. Fortunately, a few handy tips can help you get the measurements you need:


  • Check during spring and fall – Measure your baby at the beginning of spring and fall. These transitional seasons often mean significant shifts in temperature, requiring different clothing types.


  • Measure two months ahead – If possible, measure your baby two months before a new season starts. This allows time for shopping, as well as adjusting for any unexpected growth spurts.


  • Consider layers – When measuring, consider layering. For colder months, ensure that there’s room for layers under outfits, and for warmer months, prioritize breathable, lightweight fabrics. See more tips on keeping your newborn warm at night.


By timing your measurements appropriately, you can plan for seasonal needs and ensure your baby’s comfort.

Common Sizing Mistakes to Avoid

Like other aspects of parenting, understanding how to measure and find the right-sized clothes for your baby is a learning experience. However, you don’t need to start from square one. To set yourself up for success, avoid these common sizing mistakes:


  • Buying too far ahead – It's tempting to stock up on adorable outfits for your child to grow into, but buying too far ahead can lead to sizing issues. Instead of buying several sizes up, consider purchasing pieces that your child can wear comfortably now with a little room to grow.


  • Ignoring brand-specific size charts – One of the most common clothing mistakes parents make is overlooking brand-specific size charts. As mentioned, each brand has its own sizing standards, and Posh Peanut is no exception. Our size chart is carefully crafted to reflect the unique cut and style of our clothing, ensuring that each piece fits as intended.


  • Choosing based on age alone – While age can be a helpful guideline when choosing clothes sizes, it's not a one-size-fits-all solution. Children of the same age can vary greatly in size and shape. By focusing on height, weight, and specific measurements, you can make more informed decisions and select sizes that truly fit your child's unique build.


Ultimately, finding the right size for your child doesn't have to be a guessing game. By avoiding these common sizing mistakes, you can ensure your child enjoys the comfort and style of the perfect fit.

Practical Tips for Buying Baby Clothes

Still worried about how to buy the right size for baby? Consider these additional insights:

Choosing the Right Size for Different Types of Clothing

Clothing sizes vary between brands and between different pieces. This means it’s important to consider the type of clothing you’re purchasing in addition to the brand’s size chart.


For daily wear items, like one-pieces and baby rompers, items should fit true to size. You could consider buying a size up to allow for growth and longer use, as long as the item is not too loose on your little one. For seasonal items, such as jackets or holiday outfits, ensure they’ll fit during the intended season.

baby laying down wearing nature themed onesie

Prioritizing Comfort and Mobility

As mentioned, prioritizing comfort and mobility is crucial when selecting clothes and baby accessories —babies need soft, breathable fabrics that allow for movement without irritating their delicate skin. But what does this mean when you’re shopping?


You should look for clothes made from natural, gentle, and stretchy fibers.


At Posh Peanut, we’re proud to offer clothing made with our signature viscose from bamboo fabric. It’s soft, breathable, and 4x stretchier than cotton, so your little peanut can wear their favorite items longer. It practically grows with your newborn or toddler to ensure comfort both now and in the months ahead. 

Find the Perfect Size for Your Little One with Posh Peanut

Choosing the right size for your baby's clothes is essential for their comfort and happiness—plus, finding the right pieces will keep them looking adorably chic through every growth spurt.


At Posh Peanut, we make it easy to find the perfect fit with a detailed size guide that considers your little one’s age, weight, and height.


Our commitment to quality also means that each piece is designed to support growth and movement. Whether you’re looking for everyday wear or special occasion outfits, our approach combines fashion with practicality to ensure your baby feels comfortable, looks stylish, and can move and grow to their full potential.

Sources: 

1 New Mexico State University. Clothing Hints for Young Children.

https://pubs.nmsu.edu/_c/C401/index.html#:~:text=Clothing%20that%20is%20too%20small,child%20should%20also%20be%20avoided

2 What to Expect. Baby Clothing Sizes Chart and Guide.

https://www.whattoexpect.com/first-year/baby-clothes-sizes/