The Children's Place
Sugar & Jade extended tween (to size 22)
One of the only mainstream lines that runs past 18 into 20 and 22, with trend-forward tween styles and frequent sales.
Girls size 20 swimsuit: the hardest tween size to find
If size 18 is hard, size 20 is the wall. Almost no brand goes this high in kids' swim. Here are the few that reach 20 to 22, plus the women's-size pivot that saves the day when the kids' chart runs out.
Short answer:
The Children's Place (extended to 22) and SwimHer for kids' sizing, then pivot to a women's XS to S or junior plus.
Prefer more coverage? We flag modest, higher-coverage styles (rash guards, swim shorts, full one-pieces) on every list.
Where to find a girls size 20 swimsuit
A short list, because few brands go this high. Start with the extended kids' lines, then the women's pivot.
SwimHer
Makes its own extended sizes
Designs specifically for the tween/teen gap and stocks its own sizes, so it rarely dead-ends on sold-out. The best bet when 20 is impossible elsewhere.
Kohl's
Girls Plus 7–20 (SO & Lands' End)
Plus chart spans 4 to 20 in one place, carrying both budget (SO) and premium (Lands' End), with Kohl's Cash on swim.
Lands' End
Women's Plus 1X–3X (modest, UPF 50)
When the kids' chart runs out, Lands' End women's plus is the smoothest step up: long torso, modest cuts, true UPF 50.
Amazon
“Girls size 20 swimsuit” & juniors plus
The widest net for an unusual size, including junior plus and women's options that fit a size-20 tween. Read reviews for true fit.
Size 20 questions, answered
Where can I find a girls' size 20 swimsuit?
Very few brands go to 20. The Children's Place Sugar & Jade line runs to size 22, SwimHer makes its own extended sizes, and Kohl's carries girls plus to 20. After that the smart move is to pivot to a women's XS to S or a junior plus, which often fits a size-20 tween better than hunting a sold-out kids' 20.
Is size 20 the end of girls' sizing?
For most brands, yes. The girls' chart typically stops at 16 or 18, and only a few reach 20 to 22 in extended tween lines. Once she needs a 20, you are effectively shopping the very top of kids' plus or the bottom of women's, so it pays to compare both.
Is a girls' size 20 the same as a women's size?
A girls' 20 lands near a women's XL or 1X in the chest and waist, but with a shorter, kid-proportioned torso. If she has a teen's height and shape, a women's XS to S or junior plus usually fits better. Measure chest, waist and hip and compare to the women's chart before buying.
Related: girls size 18, size 16, junior plus swimsuits.