Previous answer was: "You should start going into juniors sizes like 0 or 1. You no longer should shop in the girls section anymore. Juniors is just a little bit bigger than girls sizes and its not as big as womens. Good luck!"
I disagree strongly. I have an 11 year old who is 5'8" tall with 40" hips in size 18 plus now. Such a child will certainly not fit into a size 0 or 1 Juniors when we need to size up. You would probably need 11 or 13 in Juniors to match the hip, but other proportions may be off. Best bet is to take good measurements and try to match this to the size charts, then try things on. 18 plus has a shorter inseam compared to misses regular, so when we size up we may consider a petite 12 in bottoms, sticking to modern (lower) cut to avoid the problem that prepubescent girls don't have a shape with a smaller waist.
Junior size 4 to 6 Loose fit
It would be equivalent to a 0. Or in some cases, a 1.
The answer is in the question, to be exact junior plus size would be around L-XL and junior size is around (a big) S-M.
Go to www.swimsuitsforall.com. There you will be able to find a great selection of junior plus size swimsuit that you will really like.
22 but that doesn't exist
A size 10 or 12 in ladies would be the equivalent of a size 13 junior's pants. Junior sizes are cut more straight through the hip and thigh as most teenagers are thinner through this area.
They use a size 5 netball
Junior sizes are odd numbers. Woman's are even numbers. So size 16 is a woman's size already. Many brands of juniors go past the traditional size 13. Which is great for younger who want to wear the current trends. So a woman's 16 is a juniors 17. 16/17 14/15 12/13 10/11 8/9 6/7 4/5 2/3
There is no equivalent. The size is progressive
A women's size 6.5 shoe is equivalent to a size 4.5 in youth.