T size stands for toddlers, and 1T clothes are designed to fit toddlers who are up on their feet and have started moving around. This size is close-fitting than baby sizes measured in 12 to 18 months, and the clothes are also slightly longer.

However, a lot of confusion arises between 1T and 12 months because they are often mistaken for each other. But in general, 1T size is ideal for babies that are bigger than 12 months clothing but smaller than 18 months clothing. So, 1T is a medium size for babies.

You must know much more to understand 1T vs. 12 months sizes, and we have elaborated on this with details. Keep reading to learn more about baby clothes size charts.

Read our guide on 24 Month Vs. 2T.

What Size Is 1T?

1T clothing size is for toddlers that are almost 1 year old. But the sizing isn’t similar to the baby’s size because these clothes are designed for babies who can walk around. This sizing allows mobility, and the differences can also be indicated from early toddlers to those out of diapers.

When a baby is out of the diaper, it is easier to wear bottoms with a trimmer fit as there is no need for room to accommodate a bulky diaper. There is also no need for waistbands to pull off and on to change the diaper.

Some toddlers range in age from 1 to 3 years old, and their clothing is also labeled as 1T, 2T, and 3T. Different retailers have sizing charts and consider the weight and height of the baby to label the clothes size. According to Kohl's sizing chart, the smallest toddler of 1 to 2 years should be 30 lbs and 35 inches to fit into 1T clothes size.

What Is Size 12 Months?

Clothes size labeled as months is for babies who wear diapers and crawl instead of walking. The 12-month clothes are for a one-year-old baby who wears diapers, and it is important to have extra space to accommodate diaper bulkiness.

According to Carter’s sizing charts, babies around 1 year with 21 to 25 lbs weight and 28.5 to 30 inches height fall under 12 months clothes size category. This size also means up to 12 months which can be between 9 to 12 months or 12 to 18 months.

Here are some sizes mentioned by different companies for 12 to 18 months babies:


Age of Baby



Children’s Place

12 to 18 months

26 to 28 lbs

30.5 to 32 inches

Land’s End

12 to 18 months

25 to 28 lbs

30.5 to 33 inches

LL Bean

12 to 18 months

22 to 25 lbs

29 to 32 inches

Ruffle Butts

12 to 18 months

20 to 26 lbs

29 to 32 inches

What Is Size 12 Months
Read our guide on 4 vs. 4t.

What Is 18 Month Size? 1T Vs. 18 Months

The 18 months clothes size refers to 18 months old babies. This size perfectly fits babies having 25 28 lbs weight and 30 to 32 inches height. The 18 months size is similar to 12 months babies who wear diapers and have started to learn to walk.

1T size equals 12 and 18 months, but weight and height can introduce changes. 1T size fits a bit smaller than 18 months as it overlaps with 12 months size. The 18 months clothes size is bigger, with more room and more freedom of movement for active babies.

However, this sized clothing has a less mature design as it is made of babies, not toddlers.

Is 1T The Same As 12 Months?

No, 1T clothes size is not the same as 1 month because it is a bit larger and specifically designed for walking babies.  The features of 1T clothes size are diverse, such as long pants legs.

1T clothing size isn't common in the UK, but 2T and 3T sizes are more common in the US.

What Size Does 1 Year Old Wear?

What Size Does 1 Year Old Wear

The clothes size for a one-year-old varies depending on the height, weight, and mobility of the baby. Also, there is a huge variation in the sizes from one brand to another. However, having a brand size chart will help you understand and find the right-sized clothes.

Most one-year-old babies are large enough to wear for 18 months, while others can be too small to fit in even 12 months. So it completely depends on the growth.

But for simple elaboration, we have shared an average sizing chart so you can have a slight idea about baby clothes sizes but remember, each brand has a different size chart.


Age of Baby





Up to 5 lbs

Up to 17 inches



5 to 8 lbs

Up to 20 inches 


0 to 3 months

8 to 12.5 lbs

20 to 23.5 inches 


3 to 6 months

13 to 16.5 lbs

24 to 25.5 inches


6 to 9 months

17 to 20.5 lbs

26 to 27.5 inches


9 to 12 months 

21 to 23.5 lbs

28 to 30.5 inches 


12 to 18 months 

24 to 25.5 lbs

31 to 32.5 inches 

The perfectly fitting clothes for babies shouldn’t be too tight to allow easy mobility. Therefore, it is best to focus on the baby’s clothes features. We highly recommend not buying baby clothes with buttons but prefer zipper pajamas or simple clothes for your one-year-old.


1T Vs. 12 Months - What Is The Difference?

The 12 months clothes size is for 1-month-old babies, which means the size is comparably smaller than 1T. In a 12-month size, there is more area for diapers, and zippers are attached to make it easy to change diapers.

The size is also longer in 1T compared to 12 months. However, you will not find diaper flaps, zippers, and snaps in 1T clothes size.

Also, the 12 months size is more common, while 1T size is occasionally found. At most places, 1T size is equivalent to 12 months. But you can know the difference when both sizes are available at the store.

You can check the sizing chart for a better understanding, as the Etsy chart will help you in this regard; a size range is available from 3-6 months to 1 T, 2T, 3T, 4T, and 5T.

How To Find Right Sized Clothes For 1-Year-Old Baby?

Here are a few tips and helpful guidelines you must consider when buying the right-sized clothes for a 1-year-old baby.

  • Choose only the most practical options by prioritizing quality over quantity. You don’t need too many clothes for your baby as they grow rapidly.
  • Buy at least one size up for your baby, such as for your 6 months old baby, get 9 to 12 months size clothes. Do not get 2 to 3-size-up clothes as they will be too big for your 1-year-old.
  • Do not buy too big or too small clothes. Along with the size, always prefer the comfort of your baby.
  • Pick clothes with easy fastenings, such as pants and leggings with elastic waistbands are better options than clothes with buttons.
  • Cotton material is an excellent option in clothing due to comfortability and keeps the child at ease.
  • Buy clothes with non-starchy labels and buy clothes with ornamental embellishments that can irritate a baby’s skin.

Final Thoughts

The major difference between 1T and 12 months size is how the clothes are made. If your baby has started walking, choose 1T size clothing; if the baby isn’t walking, go for 12 months size.

1T size isn’t common in US retailers, but on online stores such as Amazon and Etsy, you can get this size. If you find 1T and 12 months size listing in one place, you should know that 1T is designed for mobile babies. When you find it confusing to choose between 1T, 12 months, and 18 months clothing, go for sizes up to 18 months as babies grow faster.

It is not mandatory that the clothes size babies are wearing may match their age perfectly. Your baby may easily wear multiple sizes up to 1 year from 1T to 12 months and 18 months sizes.

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