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The standard sizes in children's clothing assumes your child has an average build. But what if he or she doesn't? Fortunately, there are several children's clothing stores which in addition to the standard sizes, also offer sizes for those with slimmer or larger builds.
Such sizing is known as extended sizing. You do not need to shop at specialty stores get these extended sizes.
Names of extended sizes
Firstly, let's make go over the names of these sizing groups since they're different for boys and girls. For boys that are tall and slim (basketball player build) you'll want slim sizing. For boys who are built like a football player, you'll want husky sizes. For a slender girl, the sizing is slim. For a girl with a stronger build, the sizing is plus. That's the case across all children's extended sizing in the US.
If you shop at a place with extended sizing, a letter beside the size will reflect that. For example, size 6H for a boy means a size 6 husky. A size 7S for a girl means a size 7 slim. And so on.
Is average build labelled as such?
In a few stores yes, and in that case it will have an R after the size number (e.g. 5R). In most stores though, regular sizes aren't labeled so if a size does not have a letter after it (e.g. 5), then it's simply a regular size.
How do I know if my child needs extended sizing?
You'll probably already know if your child needs extended sizing because clothes in regular sizing simply don't fit right in all areas at once.
For example, both my boys are tall and slender. If I purchase pants in the size for their age in average build, it'll be OK in length, but the waist will be much too large. But if I go down below their age level, the waist finally fits correctly but now the pants are too short. This is not a look you'll want for your kids, and I didn't either! So, bring on the extended sizes, I say.
Affordable children's clothing stores that offer extended sizing
There are many children's clothings shops which offer both regular and extended sizing at price points which won't break the bank. These sizes are only available in certain clothing items, usually jeans, pants and shorts. Some stores offer extended sizing for other items as well, like tops and skirts.
My main go-to for extended sizes is The Children's Place. Most of their pants are available in extended sizes, and even better, these are even more likely to be in stock than the same product in regular sizing. You can go directly to their line of boys extended sizes here and girls extended sizes here.
Old Navy also has a good selection in extended sizes, including some of their tops in the case of boy's husky and girl's plus sizes. You can find their items in boy's slim here, boy's husky here, girl's slim here, and girl's plus here.
OshKosh B'gosh stocks extended sizes, but there's not an easy way to find out at a glance all items that have it. Fortunately, you can work around that conveniently by going to the category you desire (e.g. jeans) and then filtering by size. In the size options, they'll list any extended sizes that are available (e.g. 7S) so you can filter according to your child's size. If only regular sizes are listed, then it means that items in that category aren't available in extended sizes. While OKBG is the priciest of the stores listed here, they can be surprisingly cheap when they have a sale running.
Carter's, being the budget-conscious sibling store to OKBG, has the same setup as OKBG where you can filter by size.
How to order extended sizing online
If you only ever bought regular sizing before, you may not have even realized that extended sizing was available. You can select this option on the product page, as shown in the pic below. It's a similar setup across all the US children's clothing stores which offer it.
Below we can see an example from The Children's Place, with their girl's bootcut school uniform pants.
Sizing will always default to regular, so if you need one of the other options, be sure to select it, as shown in the pic above. This sounds obvious, but there've been so many times I nearly ordered the regular sizing instead of slim for my boys. Double-check the sizing in your cart or at checkout (in fact that's a good thing to do anyway, even if you're just shopping regular sizes).
As mentioned earlier, not all items from every store will come in extended sizing.
Active pants that you'd use for PE or for after-school sports activities usually do not come in extended sizes. (I did find some one time from The Children's Place, but it's rare.) Don't worry! Some brands have sizes that just naturally happen to lean a little more in one direction or the other, so this is my guide for PE pants.
If your child has a slim build, you'll want to check if The Children's Place has active pants available in slim sizing. Otherwise shop at Carter's or OshKosh B'gosh. I find that the waist at both of those last two stores is narrow enough compared to the pants length that it's a reasonably good fit for your slim child.
If your child has a larger build, you'll want to get their PE pants from The Children's Place. Their regular active pants tend to have a looser waist.
Old Navy PE pants are somewhere in the middle.
There are many affordable children's clothing stores mentioned above which offer sizes for all builds.