Online and in store, you may have seen sizes of children's clothing with the letter T in them, such as 2T, 3T, 4T and 5T. This simply means toddler sizes. As a rule of thumb, the number corresponds to the child's age. For example, the average 4 year old would fit a size 4T.
If you're buying something for your child, don't stress about the fact of the letter T. Simply buy it according to the number before the T. That number should match your child's age. There are a few things to be aware of though.
Some children's clothing stores sell a size 24M and a size 2T - how to know which size to pick
For stores which sell both a 24 months and 2T size, both can work for a 2 year old, but be aware there is a very slight difference between 24M sizing and 2T. The size 24m is going to be slightly smaller than the 2T.
So decide accordingly which one your toddler needs. For example, if your toddler has just recently outgrown size 18m clothing, then size 24m is your best bet for the next step up. On the other hand, if you're buying ahead for a little later in the season then you might like the 2T because it's a bit bigger since it won't be worn right away.
Some kids clothes stores sell a size 5T and a size 5 - how to know which size to pick
If you're shopping for kids clothes online or in store and the same store sells both a size 5T and a 5 (or a 4T and a 4, and so on), the sizes will be slightly different with and without the T. In this situation the size 5T will be slightly smaller than the size 5.
Again, your choice of which to pick depends on if your child has just recently outgrown their 4 year old sizing. If so, then a 5T is what you want. If your child already has mostly 5T's and is not wearing any size 4's or 4T's any more, it's probably time to get a size 5.
Where to shop for toddler clothes
I've compiled a list for you here of my favorite popular U.S stores for cute yet affordable toddler clothes online. Enjoy!
If your child is smaller or bigger than than other kids his or her age
If your child tends to be smaller or bigger than the average child of the same age, bear this in mind when shopping for children's clothing. The size number as age (e.g. 3T fitting a 3 year old, 4T fitting a 4 year old) is only approximate. In general, this works well for T-shirts, but not so well for things where an exact fit is more important, for example long pants.
If your child is particularly short or tall then be aware long pants may not fit properly if you base it on age alone. For example, you might need to size up for a particularly tall child or down for a short child.
Don't stress too much - remember, you likely already have a good feel for the size based on what items of that sort are already in your child's closet and how the sizes are currently fitting him or her.
But if you're buying a fitted item for a young relative instead of for your own child, it may be worthwhile to check in with the parents to check on the child's size for that type of item. For example, ask what size in long pants, or what size in shorts, and so on. If in doubt or if you want to keep it a surprise, too large is better than a little too small.