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The tag says 130. Your kid is seven. Nothing about that math is obvious when you're standing in a fitting room, or squinting at a size chart at 11 p.m. with a school year bearing down on you.
Here's the secret that makes it all click: that number is a height. A size 130 is cut for a child around 130 centimeters tall. Once you know that, number sizing stops being a puzzle and becomes the most honest system in kidswear, because it measures the kid, not a guess about their age.
This guide converts every number size from 100 to 170 into US sizes, covers baby sizes from 59 to 90, and shows you the 30-second measuring routine that makes every chart easier to use. If you want the deeper story on fit itself, our complete guide to kids' activewear is the place to start.
Number sizes are height sizes
Most brands from Asia and much of Europe size children's clothing by height in centimeters. The system runs in steps of ten: 110, 120, 130 and so on. Each step fits a child whose height falls roughly within that band.
US sizing works from age instead. That's friendlier at first glance, but seven-year-olds come in a wide range of heights, which is why two American brands can disagree about what "size 7" means. Height doesn't argue back.
The ten-second rule
Measure your child's height in centimeters and round up to the nearest ten. A kid who is 127 cm wears a 130. That's the whole trick. When in doubt between two sizes, take the bigger one; growing into clothes takes a month, growing out of them takes a weekend.
The conversion chart: 100 to 170 in US sizes
| Number size | Height (cm) | Height (in) | US size | Typical age |
|---|---|---|---|---|
| 100 | 95–105 | 37–41 | 3T–4 | 3–4 yrs |
| 110 | 105–115 | 41–45 | 4–5 | 4–5 yrs |
| 120 | 115–125 | 45–49 | 5–6 | 5–6 yrs |
| 130 | 125–135 | 49–53 | 7–8 | 7–8 yrs |
| 140 | 135–145 | 53–57 | 9–10 | 9–10 yrs |
| 150 | 145–155 | 57–61 | 11–12 | 11–12 yrs |
| 160 | 155–165 | 61–65 | 13–14 | 13–14 yrs |
| 170 | 165–170 | 65–67 | 15–16 / XL | 15–16 yrs |
So if you've been wondering what size 120 is in children's clothes: it fits most five- and six-year-olds, somewhere around 45 to 49 inches tall. A size 130 lands in US 7–8 territory, and a 140 translates to roughly a US 9–10.
Two honest caveats. Ranges shift a little from brand to brand, so a quick glance at each brand's own chart is never wasted. And from 150 upward, kids' sizing starts overlapping with junior sizes, which is why a tall eleven-year-old and a petite fourteen-year-old can share a wardrobe and both deny it.
When the systems disagree
Here's the scene: the same seven-year-old wears a 130 in one brand, an 8 in another, and a "M" in a third. Nobody is lying. The brands are just answering different questions. Number sizing answers "how tall is the child"; US sizing answers "how old is a typical child this size"; letter sizing answers "how few labels can we print."
European brands mostly share the centimeter system, so a 128 from a German label and a 130 from ours are cousins, not strangers. UK brands lean on age ranges. American brands add slim and husky cuts on top, which fixes width but muddies comparisons further.
The way through is unglamorous and works: trust height first, then check the garment's own measurements when a piece has to fit precisely. Age on a label is a rumor. Centimeters are a fact.
Baby sizes: 59 to 90, by month and by weight
Baby clothes use the same logic, just in smaller steps. The number is still the length of the baby in centimeters.
| Number size | Age range | Typical weight | US equivalent |
|---|---|---|---|
| 59 | 0–3 months | 6–12 lb | Newborn / 0–3M |
| 66 | 3–6 months | 12–16 lb | 3–6M |
| 73 | 6–12 months | 16–20 lb | 6–12M |
| 80 | 12–18 months | 20–24 lb | 12–18M |
| 90 | 18–24 months | 24–28 lb | 18–24M / 2T |
Size 70 sits between the 66 and 73 in brands that cut in smaller steps, and fits most babies around six to nine months. Size 80 baby clothes are the workhorse of the second year: roughly 12 to 18 months, though sturdy walkers get there sooner.
Shop by weight for the first year
Newborn clothes are sized by weight as much as by month, and weight is the number to trust. A chart can say 0–3 months, but babies write their own schedules; newborn sizes generally fit up to about 12 pounds, and most 0–3 month clothes top out around 12 to 13 pounds regardless of what the calendar claims.
If a baby is bumping against either the length or the weight ceiling of a size, move up. Nobody has ever regretted a onesie with room in it, and gift-givers take note: buying two sizes ahead is the move that makes you look clairvoyant in March.
How moodytiger sizes run
We cut true to height, then add room where movement needs it: across the shoulders for climbing arms, through the seat for the crouch-and-spring of playground physics, with waistbands that stretch instead of dig. You'll see both number and US sizes on our charts, so whichever system you think in, you're covered.
A few category notes worth knowing. Tops run relaxed on purpose; a tee that fits like a second skin loses the fight with a jungle gym. Leggings are the opposite, snug by design, which is why they get their own chart. Outer layers are cut with the layer underneath in mind, so a jacket in your kid's usual size still zips over a hoodie in October without the sausage effect.
Category matters, though. Leggings hug and forgive; woven layers don't stretch the same way. Before you order, the leggings size chart is worth thirty seconds, and our guide to how kids' activewear should fit covers the squat test and the reach test in detail.
Between sizes? Size up
Kids this age grow around two to three inches a year. Buying for the season ahead, not the fitting room mirror, is the quiet money-saver of kids' clothing. A little length at the ankle in August is a perfect fit by October.
Measure once, shop easy
You need a wall, a book and a pencil. Shoes off, heels against the wall, book flat on the head, mark the wall, measure to the floor. Do it in the morning if you're feeling scientific; we all shrink a few millimeters by dinner.
While you're there: chest measured under the armpits, waist at the belly button, both with one relaxed finger of slack. Write the numbers inside a kitchen cupboard door. Re-measure at the start of each season, or whenever pants start looking nervous about the ankles.
Three checkpoints a year is plenty for most kids: back-to-school, the winter holidays, and sometime around spring break. Growth spurts don't follow the retail calendar, but those three dates catch most of them before the wardrobe does anything embarrassing.
Quick answers on kids' sizes
What size is 100 in children's clothes?
Size 100 fits children about 95 to 105 cm tall, which is 37 to 41 inches. That converts to a US 3T–4, most often a three- or four-year-old.
What size is 110 in children's clothes?
A 110 fits children roughly 105 to 115 cm tall, which is 41 to 45 inches. In US terms that's a 4–5, typically a four- or five-year-old.
What size is 120 in children's clothes?
Size 120 fits children about 115 to 125 cm tall, which is 45 to 49 inches. That converts to a US 5–6, most often a five- or six-year-old, though a tall four-year-old gets there early.
What size is 130 in children's clothes?
A 130 fits children roughly 125 to 135 cm tall, which is 49 to 53 inches. In US terms that's a size 7–8, typically a seven- or eight-year-old.
What size is 140 in US sizes?
A size 140 in US sizing is about a 9–10, fitting kids around 135 to 145 cm (53 to 57 inches), most often nine- and ten-year-olds.
What size is 150 in children's clothes?
A 150 fits kids about 145 to 155 cm tall (57 to 61 inches), which is a US 11–12. Junior sizing starts to overlap here, so check sleeve and inseam lengths rather than trusting age labels.
What size is 160 in children's clothes?
Size 160 fits kids about 155 to 165 cm tall (61 to 65 inches), which is a US 13–14, typically a thirteen- or fourteen-year-old.
What size is 170 in children's clothes?
A 170 fits teens about 165 to 170 cm tall (65 to 67 inches), which lands at a US 15–16, or an XL in youth ranges. From here, most wardrobes graduate to adult sizing.
What size is 70 in baby clothes?
Size 70 fits babies about 70 cm long, usually six to nine months old and somewhere in the 14-to-18-pound range. Between sizes, take the larger one and cuff the sleeves for a few weeks.
What is 16Y in size?
16Y is the top of most youth ranges, cut for teens around 160 to 170 cm (roughly 63 to 67 inches). It corresponds to a number size 160–170, after which most kids move into adult XS or S.
Do all brands size the same way?
No, and that's the polite version. The height bands above hold for most number-sized brands, but cuts differ, which is why the measuring routine matters more than memorizing any single chart.
Sizes are just the boring paperwork of a wardrobe. What matters is that nothing pinches, nothing drags, and nothing gets between a kid and recess. If back-to-school shopping is on your list this month, our back-to-school checklist pairs well with this chart, and the full collection is ready when you know your numbers.
