Is 4t A Youth Small

Is Youth XS equal to 2T, 3T or 4T? 3

I want to buy a church shirt for my son. The site has no size information and instead says 2Q, 3Q etc. Say xs, small, medium, large or xl. They come children, young and old. I think he's younger than the boy, right? I tried searching but couldn't find the size chart. Anyone have an idea?

update

Sorry, I'm actually asking for XS.

My son wears a 4T shirt ... and we recently found out that the XS children's shirt would fit in it ... the size of the XS is 46 I know ...

Here is a good size chart for reference.

XS youth size table

Is 4t A Youth Small

My daughter wears a 4T and it also fits in an XS shirt (size 4/6). The XS pants are too long, but the shirt is perfect and you can still grow.
According to various websites, XS is a 2Q3T. I agree, it's really annoying when the retailer doesn't tell you the actual size.
Very young
The young xs have no size 68, no children ...
The size of the children's XS space is 4.