Is there anything cuter than baby apparel? Think about it—tiny shoes with miniature laces, hats and mittens that look made for a doll, and of course, wee little knit socks that look like thumb-warmers.

While the smallness of baby clothes may melt your heart, sizing for baby items might throw your head for a loop. You might find yourself squinting at labels wondering, Should I give clothes that fit the baby now, or buy ahead–and if so, how much larger should I buy? How should I understand the labels on the baby clothes?

Whether you’re looking for a friend or buying for your own little one, understanding clothing sizes can often feel a little confusing. A size chart is a good place to start looking at baby clothing sizes but here are a few tips and tricks to help you browse with confidence (and enjoy the cuteness).

4 Essentials of Baby Sizing

Finding a baby's clothing size may be confusing, but if you’re new to the wide world of baby sizing, don’t fret. Shopping for another individual, whether a baby or an adult, can be puzzling especially when you don't have the exact size or measurement. There are just four things you need to know to master your shopping trips to the baby aisle.

#1 Sizing Standards are Based on Age

Even though baby clothes are sold by “age,” they’re really broken into groups based on the baby’s height and weight.

Here’s why: babies grow at all different speeds depending on genetics, the stage of their development, and so much more. This means that it is likely that your sister’s cherubic six-month-old fits into clothes size 12-18 months.

When in doubt, check the sizing chart (ours is below!) to ensure the perfect fit.

#2 It’s Smart to Buy Ahead of Growth Spurts

As mentioned above, babies are champion growers. In fact, from the moment they’re born to about six months, a baby may gain up to 7 ounces and grow ½ to 1 inch…every week. By the time a baby is blowing out her first birthday candle, she’ll have likely tripled her birth weight.

If you’re shopping for a gift, it’s a good idea to buy ahead of the baby’s current age so that they have plenty of time to wear and grow into the clothes. Don’t forget to think about what season it’ll be when they wear them.

Dress you baby for comfort and style. Start shopping today!

#3 Newborn Sizes Are A Win for New Mom Gifts

For shower gifts or babies on the way, buying a newborn size usually gives you enough wiggle room since newborn clothes fit a wide range—babies around five to nine pounds. So getting the right size for a newborn might be the easiest.

#4 Know Your Options

If you’re not sure about the baby’s age, length or weight (your boss isn’t big on small talk) you’ve got a few options:

  • Buy extra big (they’ll grow into it eventually, trust us).
  • Double check the return policy
  • Opt for a cozy blanket or cute set of burps or bibs

Other Factors To Consider

Besides the above, there are still some other details to keep in mind when shopping for baby clothes bundles.

  • Different brands of baby clothing are sized differently – Make sure to double-check the specs on the clothes you’re considering, and don’t assume that all sizes are created equal. Different brands may have different sizes.

  • Become familiar with what the label means – Have you ever tried on a t-shirt labeled size medium and have it feel too big, then tried on a “Medium” from a different brand and have it be too small? As maddening as it is, different brands will have slightly different takes on sizing. Luckily, you can usually find sizing charts on the brand websites so you can choose the best clothes for your baby.

  • Consider fabric type – As you’re pursuing the racks (or scrolling through online stores), pay attention to fabric type. Baby skin is particularly sensitive, so it’s always smart to be cognizant of what will be rubbing against their tender chubby leggs and arms all day long. The best fabrics for baby clothes are cotton, bamboo rayon, fleece, and linen.

How Much of Every Size Do I Need?

Now that you know your little one is a champion grower, you might be wondering how many of each size you need to get you through your child’s babyhood. First, let’s start with how many basics you should have that suit your child’s current size:

Don’t forget to factor laundry into this equation. If you’re doing a load every day, you can probably get away with sticking to the lower range of clothing items. If you’re doing a load one or twice a week, stock up on baby outfits.

As for sizing, a good rule of thumb is to have 2-3 clothing items from each category be a size or two up.

Newborn Baby Clothes Sizes

When buying for newborns, it’s best to size up just a little. Most “newborn”-sized clothes only fit babies up to 8 pounds—all babies would quickly grow out of that, and some babies enter the world even larger than that.

Plus, who says you can’t roll up sleeves and pant legs for a little while as baby keeps growing?

Preemies or petite babies may fit well into newborn clothes. Just remember to keep the tags and receipts for them, in case the baby comes a bit bigger than expected.

Take a Peek at How Monica + Andy’s Sizing Works

At Monica + Andy, we make it simple and straightforward to buy the perfect clothes for the baby. Below is a handy sizing list to keep on hand when shopping at Monica + Andy.

  • Preemie – Up to five pounds and 17 inches
  • Newborn – 5 to 9 pounds, or up to 20 inches
  • 0-3 Months – 9 to 12 pounds, 18 to 23 inches
  • 3-6 Months – 12 to 16 pounds, 23 to 26 inches
  • 6-9 Months – 16 to 20 pounds, 26 to 28 inches
  • 9-12 Months – 20 to 24 pounds, 28 to 30 inches
  • 12-18 Months – 24 to 27 pounds, 30 to 31 inches
  • 18 to 24 Months – 27 to 30 pounds, 31 to 33 inches
  • 2T – 29 to 32 pounds
  • 3T – 32 to 35 pounds
  • 4T – 35 to 39 pounds
  • 5T – 39 to 43 pounds

Find The Perfect Fit with Monica + Andy

When it comes to finding the perfect clothing for the little one in your life, understanding how baby sizing works can help ensure they’ll get plenty of use out of that adorable watermelon-patterned onesie (and save your head from spinning). But for a fit that feels just as good as it looks, you need clothing made from the right kind of fabric. That’s where Monica + Andy comes in.

At Monica + Andy, all of our baby clothing is made from GOTS-certified organic cotton. That means you get cloud-soft fabric that’s gentle on baby’s sensitive skin and free of harsh chemicals. Whether you’re looking for the best new baby gift for a friend or for your own little one, we’re here to help. For a fit that’s cozy, cute, and most importantly, safe, shop Monica and Andy.


  1. Weiss, Kerry. "Baby Clothes Sizes: How to Choose the Correct Clothing Size for Your Infant." What To Expect. 12 August, 2021.
  2. Fabian, Weber-Nicole. "Baby clothing sizes, explained: What you need to know to shop for infants at every size." Care. 16 July, 2021.