1T vs 12 Month Baby & Toddler Clothing Size Explained

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Figuring out baby sizes is like walking through a bewildering maze of cuteness.

Darling dresses, cuddly rompers, or teeny tiny suits grab for your attention as you’re shopping for your one-year-old, but when you have to choose a size, you could be offered 9-12 months, 12 months, 12-18 months, 1T, or 1-2T.

You won’t see all of these sizes everywhere, but in case you do:

What’s the difference between 1T vs 12 months clothes?

1T is not a common size found in most U.S. stores, but it does pop up occasionally. Expect minimal differences between 1T vs 12 months clothing — 1T may have less diaper room and may be a little bit longer and bigger overall (12 months means up to 12 months), and probably will have fewer baby features like flaps and snaps to access the diaper area. But otherwise these sizes are similar. When in doubt, buy big — kids grow fast!

This article will describe how sizing works, and give you some tips on how to choose clothing that will be the most convenient and comfortable for your child. The better their clothes fit, the better little ones will feel. A good fit frees up their movement as they learn to navigate their world.

What Size is 1T?

Any number with a T after it is designed for a toddler – a child who is up on their feet and moving around.

Typically, toddler sizes still have room for a diaper but may fit a little more snug than baby sizes (measured in months).

They’re also longer than the equivalent baby sizes. 1T could also be perfect for an older toddler who is small.

So 1T would be a great size for a 12 month / one-year-old who can walk, or it would also fit an older toddler who is on the smaller size.

Size 1T is hard to find, however.

Amazon’s Kimocat store does list some little suits (super cute!) as 1T, but their sizing charts don’t list a 1T description.

According to a sizing chart from Kohls, their smallest toddler size, 1-2, fits a child up to 30 lbs and 35″ tall.

Usually if 1T shows up at all, it’s listed as 1-2T.

Unfortunately, baby and toddler sizing doesn’t seem to have the tightest regulation. You really do need to know your child’s height and weight at least, and check the sizing charts of the brand you’re considering.

What Size is 12 Months?

Any numbers with months after them are designed for babies – children who are still wearing diapers and crawling rather than walking.

These clothes accommodate diapers – they have more space in the hip area and often have snaps or zips to make it easier to access the diaper to change it.

So 12 months is a good size for a one-year-old baby that’s still crawling and/or requiring frequent diaper changes.

Randomness in sizing also applies to baby clothes. You need to check the brand sizing chart.

Something else to know – if something is described as 12 months, that is usually shorthand for up to 12 months.

So 12 months and 9-12 months are about the same thing. 18 months and 12-18 months are about the same thing.

The most common listings for 12 months sizes are 20 to 24 lbs in weight, and 24 to 28 lbs. for 18 months. But again, it’s not universal.

Check out the differences listed in sizing charts for these companies:

  • LL Bean, 12-18 months: Height 29-32″, Weight 22-25 lbs
  • Land’s End, 12-18 months: Height 30.5-33″, Weight 25-28 lbs
  • Ruffle Butts, 12-18 months: Height 29-32″, Weight 20-26 lbs.
  • Children’s Place, 12-18 months: Height 30.5-32″, Weight 26-28 lbs.

And you probably have to figure this out in a state of sleep deprivation, while you’re nursing or rocking someone to sleep, right?

So What’s the Difference Between 1T vs 12 Mos?

Since 12 months means up to 12 months, this size will usually be smaller than 1T.

There will also likely be more room in the diaper area, and depending on what article of clothing we’re talking about, chances are there will be snaps or zippers to help you with diaper changes.

1T will likely be longer than 12 months, may feature less diaper room, and will have older styling — don’t expect diaper flaps, snaps, and zippers in 1T clothing.

You may see less cutesy baby designs in T clothing, as well. The designs may seem a tad older in 1T vs 12 months.

What About 1T and 12 Mos in European Sizing?

The plot thickens – baby clothes made in Europe are sized differently.

They name their sizes after the child’s height in centimeters.

So a size 80 means a child up to 80 cm in height, which converts to 31.5″.

This size can be compared with anything between 12 and 24 months in American sizing, according to whattoexpect.com.

Tips for Finding the Right Sized Clothes for a One-Year-Old

It should always be about their comfort. When I look back at some of the stiff outfits I stuffed my little boys into because a great aunt bought them and expected them to be worn for holidays, I wonder if I was putting my desire for them to look adorable over their comfort.

Watch how your baby moves, and take notice.

  1. Can they crawl without any fabric catching at their knees?
  2. Do their pants or shorts slide off easily, or do they hang on over the diaper without being too tight?
  3. Is the crotch too low, making it hard to freely move their legs? Are any sleeves getting caught on their toys or in their food?
  4. Feel the fabric. Is it soft?
  5. When you take clothes off to change them, do you see any red marks where the elastic has been too tight?
  6. How is their temperature? Are they flushed or too sweaty in the heat? Are they shivering or feeling cold to the touch in cold weather? Their little bodies can’t regulate temperature as well as adults, so they depend on us to help them.
  7. Do they have hats that stay firmly but comfortably on their heads in the cold or the sun?

How much your baby fusses, how much they cry, how much they smile, how much they move, and how much they learn are all affected by how comfortable and well fitting their clothes are.

Wrapping Up

So in conclusion, your child may be suited to size 1T if they’re older than one but small for their age, potty trained early, or both. You’re most likely to find size 1T in formal clothes – the things we put our kids in for weddings and other special occasions.

You’re more likely to find clothes for a child around one year old in baby sizes.

If they’re not listed with a range, like 12-18 months, but only a single number, like 12 months, assume that means up until 12 months.

If I had to buy for a 14-month-old and had no other information, I would buy 18 months instead of 12 months.

Babies grow so quickly – it’s a challenge to keep them in the right-sized clothing. Staying tuned in to their height, weight, comfort levels, and what they need to move freely will help us make sure they’re wearing the best size for their needs.

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Hope this helps!