Baby Clothing Sizes Tip

Here Comes Baby Series from

My baby girl is 7 months old.  That (stinkin’ cute if I do say so myself) outfit she’s wearing?  Is size 12 months.

Baby Clothing Size Tip

She’s a big girl, but she’s not huge (well, except for her thunder thighs that I like to squeeze all day)!  The thing is, baby clothing tags can be deceptive.  If it says 12M, it likely means 9-12 months.  9M means 6-9 months.  6M means 3-6 months, and 3M means 0-3 months.

Even then, when purchasing baby clothes, it’s always best to check the label for weight and not age.  The 3M label?  It usually works for newborns 8-12 pounds.  My baby girl weighed 16 pounds at 3 months.  We were on to 6M clothing by then.  😉 My firstborn?  She wore 3M clothes until she was 5 months old.  You just never know!

As a rule, though, if the tag gives only one number, that number is the maximum age, not the minimum.   Keep that in mind when buying seasonal clothing ahead or gifts for a baby shower.   Babies grow so fast, we want them to get the most use possible out of their clothes!



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  1. Gerber clothes are the WORST for sizing. Blech.
    Thanks for the tip! I’m going to post it as today’s Daily Duh. 🙂

  2. My baby boy came into this world weighing 1/2 oz shy of 10 lbs, so it seems like he wore 0-3 month clothes for about a week, lol. Definitely don’t just go by age!

  3. I find it helpful to get a feel for each brand, because they are all the little different. Gerber stuff runs small and shrinks. Carters usually runs true to size, but may shrink a tad. I’ve find that Old Navy clothes have a wide range in each size and I can usually get my son into at least two sizes at a time. (He is currently wearing both 12-18 and 18-24). Regarding new clothes, when in doubt, check their website to see what they define each size as. Weight and height ranges can sometimes but found on tags, but are more likely found on the manufacturer site. Also, previous owned clothes (hand-me-downs and consignment sale purchases) have usually shrunk a bit from wear, so assume they are a size smaller or so. Keep in mind you may have to size up clothes for cloth diapered babies as well. My son is probably skinny enough to still weight 9 month clothes, but instead he’s wearing 12-18 month and occasionally 24 month; because of cloth diapers.

  4. Thanks for the tip, Amy. I’m sorting through all my stuff after our two foster sons left, and planning ahead for OUR baby. And oh man, I discovered I do need to go buy some newborn to 3 month stuff.

    I LOVE shopping for baby clothes.

  5. Both of my girls have been premiees, the last one is 9.5 months old and still wearing 3-6 month clothing. But she has very long arms in proportion to her body so she usually grows out of longsleeve stuff before the rest of her body catches up. I found the gerber newborn onesies worked great when she came home from the hospital and everything else she was in premie clothes. I love the circo clothing because it seems to run long and skinny, which is how my girls usually grow. It definately depends on the kid.

  6. This is a really helpful thing to share, Amy– honestly, the sizing changed from when I had I my first to my third. It used to be labelled “0-3”! They like to confuse people. 😉 Also, I would say that the majority of full-term babies need very few, if any, newborn size outfits. They fit nicely when they’re still sort of “curled up”, but, after a week or two, almost all of them fit just fine in the 3-month size.

    • Yes! We do fine with the range sizes, but when they went to single numbers that got trickier, especially for well-intentioned gift givers.

  7. Antoinette says:

    Every child is so unique and it’s amazingly wonderful! There are 3 four-year olds in our neighborhood, and they have all grown at different rates intellectually, physically, and emotionally. The oldest is the smallest and barely wears 3T. The “middle child” is a thin 4T. And our tank (the youngest) is wearing size 8/10 shirts and size 7 bottoms. It’s been that way all through their growing up so far. Clothes swapping has been an adventure to say the least :-).

    Carters’ was my favorite go-to for onesies (but I always had to double the age to get the right size for our guy) AND Walmart often sells them for cheap. Circo wears like iron. But my favorite at this point is whatever I find at the thrift store that fits :-).

  8. Good to know. I guess you never really know your baby’s body type ahead of time.

    In addition to the cloth diaper issue that someone mentioned, my other “duh” moment was that it’s a lot easier to put on clothes that are a little baggy! Sure, my baby FIT in newborn clothes, but getting them ON was another story, especially as a first-time parent!

  9. And my daughter (who’s 6.5 weeks now) JUST grew out of newborn size clothes a few days ago. 😉 She was 6 lbs. 9 oz. at birth!

    • Awww. Our firstborn was like that. She didn’t wear 12 month stuff until she was nearly 18 months old. At least “back then” they labeled the clothes with a size range so you knew what you were getting. This one number thing really throws people off.

  10. I had almost forgotten that once he outgrew newborn clothes Joshua was pretty good in 3 months. He is getting chubby and I love it!

    I kinda wish my 28 month old would outgrow his 18 months clothes … he’s been wearing them for a year.

  11. I know this is an old post, but I am amazed at how random baby clothing sizes are and how no one really writes about it. I did a side by side comparison of some of the biggest brands and wrote a post about it here:

  12. This so makes since to me now. My little one is 18 weeks…so a little over 4m. I HATE how the brands are so different in sizing. This is my first, so I’m learning and this gets frustrating. She is a chunky monkey and is breastfed. She is chubby and tall, but very proportioned dispite the numbers. She is approximately 20lb and 26in, yes, at 4m. I hear it all the time, how she “huge,” but she is healthy.

    Anyway, today, she was able to wear old navy 6-12 and 12-18, another brand 6-9, and I tried on a dress I had laid out for church in the morning that is a 6m, which is an Isobelle and Chloe, oh, and yesterday, Carter’s 9m, which is getting a little snug, but needs it for length, too. THEY ALL FIT. Makes it hard, but thankful for the variety in styles. I MUST go by the weight and height and not the size.

  13. So I should shop for my sons clothes by weight? My problem with doing so is that the outfit is for his weight but he has short limbs and then it is long on him and crinkles up right by his face when sitting! I can’t win lol……any suggestions?

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