All Your Questions About the 3-6 Month Clothes Size Answered


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Parents often have a hard time figuring out which size baby clothes they need and the 3-6 month clothes size is one of the trickiest ones to get right.

The 3-6 month clothes size generally fits babies that weigh between 12 and 17 pounds that measure between 23 and 27 inches in height. To be sure what size will best fit your baby, you must take into account his size and weight as well as the brand’s unique fit and cut rather than his age. 

Keep reading to find out everything you need to know about 3-6 month size clothing, what else might affect what size he wears, and how to know when it is time to change sizes.

When do babies wear 3-6 month clothes

During his first several months, your baby will go through an almost unbelievable number of changes. Along with smiling, starting to communicate verbally through coos and gurgles, and starting to hold his head up, your baby will also start to move out of gowns and swaddles and into full outfits, but how do you know when he is ready to upgrade to the 3-6 month size?

There are many factors that go into determining at what age your baby will actually wear 3-6 month size baby clothes, including weight, length, speed of development, and even gender, not to mention the brand of the clothes themselves. 

Babies typically wear 3-6 month clothes from about the time they’re 2.5-3 months old until they are 5.5-6.5 months. Obviously this is very simplified because each baby’s birth size and development is unique. Even if your baby falls into the expected sizing, an outfit may not fit him because of his body shape. For example, a long and lean baby may have similar measurements to his more stocky and athletic counterpart, but the two will not wear identical outfits in the same way. 

Not only is each baby’s body and development unique, but each brand of baby clothes also has its own variations in sizing and cut as well. I researched ten popular baby clothing brands and found that, with a few exceptions, the sizing charts tend to be comparable, but none are identical across all sizes.

Here is a chart that I put together showing the recommended weight and height ranges for 10 of the most popular baby clothes brands. Take a look at this information and then read on to learn more about any specific questions that you might have.

Height and Weight Chart for 3-6 Months Clothing Size

Brand3-6 month size minimum height3-6 month size maximum height3-6 month size minimum weight3-6 month size maximum weightSizing notes
Wonder Nation23.5"26"12.5lb16lbLarge size range between products
Gerber24"26"12lb16lbRun very small compared to other brands
Gap23"27"12lb17lbTrue to size
Old Navy23"27"12lb17lbTrue to size
The Children's Place24"27"14lb18lbTend to run small
Garanimals23.5"26"12.5lb16lbRuns a little large
Carter's24"27"12.5lb17lbConsidered the benchmark of 'true to size" by many
Burt's Bees Baby24"26.5"12.5lb17lbMore narrow than Carter's
Cat + Jack24"25.5"12.5lb16lbRuns a little large
Amazon Essentials24"26.5"12.5lb17lbTrue to size

What weight for 3-6 month clothes

Weight is a big factor for determining which size clothes your baby should wear but you must remember that a tall, skinny baby might actually weigh the same as a shorter, chunkier one.

Baby clothes in the 3-6 month size typically fit babies as small as 12 pounds and up to 16-17 pounds. The best way to tell if a 3-6 month size outfit will fit your child properly is to consult the sizing chart on the maker’s website.

Several brands, including Gerber, Gap, Old Navy, and Carter’s generally fit a 12 to 17-pound baby, which is fairly standard. Parents often report, however, that these brands tend to run small, perhaps due to overall fit.

The Children’s Place is the largest of the 3-6M sizes I reviewed, fitting babies that are 14-18 pounds, despite reports that the brand overall is smaller than expected.

What height for 3-6 month clothes

Height is another crucial factor for baby clothes and it’s the most likely reason that your baby will outgrow a given size.

Most 3-6M sizes are meant for a baby who is between 23 and 26 or 27 inches. A one-inch variation in size may seem insignificant, but that could potentially mean an entire extra month of wear time.

Just like your clothes from different brands may fit differently despite being the same size, you may need to try a couple of brands to find the fit that works best for your baby’s body type.

Should 6-month old wear 3-6 month clothes or 6-9 month clothes

A six-month-old child may be able to wear either – or both – the 3-6M and 6-9M size clothes, depending on his general size and development, as well as the overall size and cut of the brand.

Once your baby starts filling out the 3-6M outfits, it is helpful to go ahead and pull out the larger clothes and start trying them out. You may find that some of the outfits already fit perfectly while others are still a bit big. It is important to make sure that you don’t move into the larger size clothes too quickly because tops that are too loose can become twisted and pose a strangulation hazard, especially in sleepwear.

Should 3-month old wear 0-3 month clothes or 3-6 month clothes

Your three month old may be ready to move up into 3-6M size clothes, or be more comfortable staying in the 0-3M size for a little bit longer. It is more important to make sure that your baby’s clothes fit properly than to try and adhere to the labelled sizes.

If the 0-3M size clothes are starting to leave marks around your baby’s arms and waist or is it becoming difficult to snap, it is time to move up to the 3-6M size.

How long do babies wear 3-6 month clothes

There is no specific age at which your baby will grow into and then out of his 3-6 month clothes. It’s likely that he will start wearing the 3-6M size a couple of weeks early, but he may continue to wear it up to or past the six-month mark. 

There are a huge number of variables that go into determining how long your baby will wear his 3-6 month clothes, including birth size, gender, the overall speed of development, and brand sizing. The average baby boy will probably wear Carter’s (an average brand) 3-6M clothes from about the time he’s two and a half months old until right up to six months. On the other hand, girls tend to be a bit smaller and the average baby girl will wear Carter’s 3-6M clothes from the time she is about three and a half months old until she is nearly seven months old.

How many 3-6 month clothes do I need

The number of outfits you need will be determined heavily by how often you plan on doing laundry. For each day, you should plan on having at least two outfits plus pajamas. During the winter months, you should plan on having an extra layer for each day. Personally, I always assume that I will be behind on the laundry and try to account for an extra day or two just in case.

For example, if you plan on doing laundry just once a week, you may need as many as 24 outfits ranging from short- and long-sleeved bodysuits to long pants or jumpers. If you can manage to wash laundry twice a week, you should be able to save a lot of drawer space by only buying 12-15 outfits.

Don’t forget that you can usually do all of your baby clothes in one load of laundry because they are so small!

Should you register for 3-6 month clothes?

When you are setting up your baby registry, your first reaction may be to add the big stuff, some toys, diapers, and every single adorable newborn outfit you see. While it may be tempting to scan every variation of “I’m new here!” it is important to keep in mind that your baby will run through newborn size clothes in particular very quickly. The best thing you can do is to pick out several outfits – especially staples like white bodysuits and basic pants – in a range of sizes so that you are sure to have some clothes ready in case your baby grows out of the NB and 0-3M sizes more quickly than expected.

If your family is anything like mine, your little one will be receiving cute outfits every Christmas and birthday for his first several years. I try to make a point of requesting clothes for each holiday that will carry him until the next one so we just need to supplement his wardrobe with specific pieces instead of buying a whole new set of clothing every three months to six months.

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Josh

I'm the dad in charge of Natural Baby life. With 10 years of parenting experience across three children, I am constantly learning how to raise children more naturally. I'm passionate about doing whatever it takes to raise a happy and healthy baby! Find out more about me here.

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