
What size baby clothes to choose? A special piece of clothing can be a memorable option for a baby shower gift! You can choose something personalized- moms love seeing the name they’ve chosen for a baby embroidered on clothing. And for a 2nd child who will wear mostly hand-me-downs, it’s especially appreciated! Consider something that suits the family’s interests- a golf outfit for a baby whose dad loves golf. Or a monster truck bodysuit because big brother loves them. Those tend to be the sweetest gifts!
But sometimes the hard part is: What size baby clothes to get?!? While we can’t tell you 100% what size they’ll be on what day, we can give you a guide to help you make the best guess!
Helpful to Know
It’s also interesting to realize babies and kids can often wear two sizes well, at the same time (especially after age 6M)! I wish I’d realized this with my first child, but with my others, we always had 2-3 sizes hanging in the closet at once. Usually things are outgrown in height first, and there are only an inch or two difference between sizes. Shorts can often be worn through growth spurts, and girls can often wear dresses as tops later on. We also recommend ordering up when in doubt.
How Baby Sizing Works
Every brand is different, but with most major brands, when one age is given as a size, it means “Through”. So 3M means “through 3M” and is the same size as 0-3M for most brands. (Many babies wear a bigger size than their age range too- to make things more confusing!) Not every brand carries 9M (6-9M) size, but 12M (6-12M) usually works for those kids too. So many kinds of kids’ clothes are made of knit material, or have adjustable waists, that it really helps stretch the wearing time too. Many newborns will wear long sleeves all the time for a few weeks, but normally you want to keep in mind seasons/climate when shopping for babies (see chart).
Maybe Skip Newborn Size
The average baby is born around 7.5 lbs. This is usually a newborn size, but just barely (most newborn sizing only goes up to about 8 or 9 lbs). Some babies never wear newborn size at all, or wear it only for the hospital. The longest a baby usually wears newborn is about 1-2 weeks after their due date (even if born early- by the due date they are usually in newborn size). Therefore, for a new baby gift, I would go with a 3M (0-3M) or 6M (3-6M) size to get a little longer wear. The exception being if you are buying specifically for a coming home outfit. Usually coming home from the hospital, the baby would likely be wearing newborn size. The other thing to consider is newborn is the most common gift size many moms get, but the shortest time the baby can usually wear any size. So a mom might be even more grateful for clothes to wear later on.
Preemies
Preemies are definitely a different story, and I had 28 week twins weighing 2 lbs. Preemie size would have been huge on them at first! But there are other things to consider with preemies- they are usually in the hospital until around their due date or a couple weeks before. For micropreemies, they aren’t even able to wear clothes for a few weeks or months. When my babies were able to start wearing clothes in the NICU, they did fit best in preemie outfits. But the hospital would often put them in newborn and 0-3m clothing too-whatever was clean- and they looked cute no matter what.
A note about the NICU: hospitals have clothes they let babies borrow while in the NICU. If mom brings her own baby clothes, she has to take them home and wash them herself. Some moms, with their first child -on maternity leave- are able to spend all their time at the hospital and enjoy dressing baby in sweet clothes (this is awesome if this is your case). Other moms already have children at home and/or a job and find themselves stretched thin through a NICU experience (this was definitely me). So I actually bought no preemie clothes and appreciated using the hospital’s outfits. (I was happy to be able to donate the few preemie gifts we got to the hospital after we outgrew them!). By the time my twins left the hospital, they were in newborn size. All this to say- go with newborn or bigger sizes in most cases, even for preemies. And when buying before the baby is born- usually you can still go by their due date for when they wear what size, and by their due date they’d often be in newborn size.

The “What Size Baby Clothes?” Guessing Chart
We’ve come up with a chart to guide what you want to buy based on the occasion. Go by their DUE date (or birthdate works if they were over 7 lbs at birth). If they were born at the beginning of a month, had big brothers/sisters, born over 9lbs, etc, go with a bigger size. If they were born at the end of a month, have a history of premature births, or have small siblings, go with a smaller size. When in doubt, get the middle or larger size. The safest bet is buying for a large range of dates (like “summer”) versus a specific holiday more than a few months out. Hope this helps you choose what size baby clothes to gift for a sweet new bundle of joy!

Is 6 months the same as a baby small? l am sewing a pattern and know she is in 6 month outfits but don’t know what size small is.
Hey Hannah! With patterns, it’s really hard to say! Paper patterns from sewing stores tend to run really large and are hard to distinguish what they mean by “small”, etc. I like using online printable patterns as they are often better at sizing.
Super helpful, especially in this time of having to order everything. Just found this now but it is actually right on target exactly for my babe; however she was born 1 day at 7.5 lbs so very average!
So glad it was helpful!
Thank you!