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Under Armour Kids
Here’s how Under Armour Kids fits your child compared to other brands you might be considering, so you know before it’s in your cart.
Find your child’s size in Under Armour Kids
Enter your child’s measurements once — we’ll size them in Under Armour Kids and at 100+ other brands, each from that brand’s own published chart. Height and weight are required; add chest, waist, hips and inseam to sharpen the fit.
Your child wears one size in Under Armour Kids. What should you buy elsewhere?
Pick the size your child wears at Under Armour Kids to see which brands have the same label and measurements (twins) and which run shorter or longer (strangers) — based on each brand’s own chart.
Show the full cross-brand table (every size)
| Under Armour Kids | Size twinssame number fits the same | Size strangerssame number, different cut |
|---|---|---|
| 0-3M20.5–24" | Hanna Andersson↓ shorterMonica + Andy↓ shorter | |
| 3-6M24–27" | None — consistent across brands | |
| 6-9M27–29" | None — consistent across brands | |
| 12M29–30" | ||
| 18M30.5–33" | ||
| 24M33–35" | New Balance Kids↑ longer | |
| 2T33–35" | H&M Kids↑ longerBurt's Bees Baby↑ longerCarter's↑ longerHudson Baby↑ longerLittle Planet by Carter's↑ longerOshKosh B'gosh↑ longer+1 more | |
| 3T35–38" | ||
| 4T38–41" | Polo Ralph Lauren Kids↑ longer | |
| 438–41" | Noralee↑ longerCarter's↑ longerLittle Planet by Carter's↑ longerOshKosh B'gosh↑ longerOtter Avenue↑ longer | |
| 541–44" | Polo Ralph Lauren Kids↑ longer | |
| 644–46" | Brooks Brothers Kids↑ longerPolo Ralph Lauren Kids↑ longerFabletics↑ longerGap Kids↑ longerGarnet Hill↑ longerLands' End Kids↑ longer+4 more | |
| 6x46.5–48.5" | None — consistent across brands | |
| 746.5–50" | Garnet Hill↑ longerPolo Ralph Lauren Kids↑ longerReebok Kids↑ longerEddie Bauer↑ longerFabletics↑ longerGap Kids↑ longer+8 more | |
| YXS47–51" | — | No same-size match at other brands |
| YSM51–53" | — | No same-size match at other brands |
| YMD53–58.5" | — | No same-size match at other brands |
| YLG58.5–63" | — | No same-size match at other brands |
| YXL58.5–63" | — | No same-size match at other brands |
Sizes shown use Under Armour Kids’ girls’/unisex chart where the brand splits by gender; boys’ sizes at the same number can run slightly taller.
In short
Where the number just works. At 3-6M, 6-9M, 6x, YXS, YSM, YMD and more, Under Armour Kids lines up with every brand we track — the size carries straight over.
Where labels drift. The exceptions are the “strangers” above — e.g. at size 3T, H&M Kids, Kohl's Jumping Beans, Polo Ralph Lauren Kids cut the same number differently. Check those before you trust the label.
Bottom line: for most sizes, a Under Armour Kids number is a safe bet elsewhere — measure once, then double-check only the handful of “stranger” brands above.
Curious about a size that isn’t your child’s here? Every size, compared across every brand, lives here: Browse all size comparisons →
Under Armour Kids makes shoes, too — see how it and every other kids’ shoe brand runs (true, big, or small) and how wide each is cut: Compare kids’ shoe sizing →
Fit & the transitions that trip parents up
Under Armour Kids-specific things the size number alone won’t tell you — drawn from its own charts.
Runs true, in a trim athletic cut
The youth hoodies and layers fit true and hold up well. The one caveat parents raise is that the cut can read a touch boxy through the body with relatively short arms, so a lanky child may want to check sleeve length.
Lettered youth sizes, numeric for little kids
Big kids are lettered YXS–YXL, with a Plus line (YSM–YXL Plus) for both girls and boys; little kids are numeric. Match by measurement — it publishes chest, waist, hip and height to size against.
The youth line often beats men’s for a big kid
Many parents deliberately choose the youth line over men’s, because the men’s sizes run long. For a big kid at the top of the youth range, youth is usually the better-proportioned fit.
Specialty & inclusive fits
Which trimmer, roomier, or adaptive cuts Under Armour Kids publishes alongside its standard sizes.
What shoppers say about the fit
Community consensus
Shopper opinion · not Little & Youth’s measurementThis is what parents report anecdotally — crowd sentiment, not a Little & Youth determination. Our sizing above is computed from Under Armour Kids’ own published chart; the notes here come from public parent discussion.
Under Armour youth fits true to size, in a trim athletic cut. Parents broadly report the youth hoodies and layers fit true and hold up well, and many deliberately choose the youth line over men’s because the men’s sizes run long. The one caveat from parent forums is that the youth cut can read a touch boxy or wide through the body with relatively short arms and torso, so a lanky child may want to check sleeve length.
Based on anecdotal discussion from multiple publicly available online sources; your experience may differ.
Should you buy Under Armour Kids?
Consider it if…
- You want performance activewear — moisture-wicking layers built for sport.
- You want a brand kids ask for — strong logo appeal in youth athletics.
- You want gear that lasts the wash — durable technical fabric.
Think twice if…
- You want everyday non-athletic clothes — it’s a performance line, not a full wardrobe.
- You have a very lanky child — the youth cut can run short in the arm.
- You’re on a tight budget — it’s mid-tier priced; best on sale.
Skip the cross-referencing — let Little & Youth do it.
Enter your child’s measurements once. We’ll show their Under Armour Kids size and their size at 100+ other brands, each from that brand’s own chart.
Find my child’s size →Shop Under Armour Kids ↗A few things parents ask that the chart won’t tell you
Should I buy Under Armour youth or men's sizes for a big kid?
Most parents prefer the youth line for a big kid because the men’s sizes run long. Youth fits true to size in a trim, athletic cut; go up only if your child is broad through the chest.
Does Under Armour youth run small?
It fits true to size for most, but the youth cut can read boxy through the body with shorter arms, so a lanky child may find the sleeves a bit short — check arm length if that’s your child’s build.
What measurements do I need to size Under Armour Kids accurately?
Under Armour Kids publishes height, weight, chest, waist, hip in its size chart. Height is the primary driver, and the chest/waist figures let you confirm body fit for a child between sizes.
Do Under Armour Kids boys’ and girls’ sizes fit the same?
From the bigger sizes up, Under Armour Kids publishes separate girls’ and boys’ charts, so the same number can differ by gender. The figures on this page use Under Armour Kids’ girls’/unisex chart.
How do I choose between Under Armour Kids’ regular and Plus cuts?
A Plus is the same numbered size as the regular cut — same length, adjusted through the waist and seat (Plus roomier). So size to your child’s usual Under Armour Kids number from the chart above, then pick the cut by build: a smaller waist for Slim, a fuller waist and seat for the roomier cuts. You don’t need a separate measurement to choose.
How do Under Armour Kids’ shoe and sock sizes work?
Under Armour Kids’ shoes fit true to size, and they’re cut wide-friendly. Kids’ shoe sizes go by foot length, not age — measure your child’s foot and match it to the size. Under Armour Kids’ socks are sized by shoe size, not age — buy for your child’s current shoe size, and if they fall between two ranges choose the smaller so the sock stays up. See how every kids’ shoe brand runs and how wide each is cut on our kids’ shoe sizing guide.
Where do I buy Under Armour Kids?
Under Armour Kids is sold on its own site and on Amazon, so you can pick the marketplace you prefer.