A baby-clothes size is not a standard. The same “3–6M” tag is built to fit a baby anywhere from about 14.5 to 20 pounds — a 5.5‑pound gap — depending on which brand printed the label. We reconciled the publicly published size charts of 30 baby-clothing brands to map exactly how far each label stretches, and which brands sit at each edge.
- The gap is real at every stage: a “0–3M” label tops out anywhere from 11 to 15 lb; “18–24M” from 26 to 32 lb; “5T” from 41 to 48 lb — all on the brands’ own charts.
- The same baby can land a full label apart between two brands.
- Some brands’ labels consistently cover heavier babies on paper (Patagonia, The Children’s Place, Gap); others lighter (Old Navy, Nike, Target Cat & Jack).
- The fix isn’t hunting for a “true size” — it’s buying by your baby’s weight and height and checking the specific brand’s chart.
How far the same label stretches, size by size
For each size label, here is the range of upper weight limits brands print for it — the lightest brand’s cutoff to the heaviest brand’s cutoff — and how many pounds separate them.
| Size label | Brands | Upper-limit range | Gap | Highest cutoff | Lowest cutoff |
|---|---|---|---|---|---|
| Preemie | 15 | 5–7 lb | 2 lb | Kyte Baby — 7 lb | Carter's — 5 lb |
| Newborn | 24 | 7–10 lb | 3 lb | Mini Boden — 10 lb | Gap (babyGap) — 7 lb |
| 0-3M | 24 | 11–15 lb | 4 lb | Patagonia (baby) — 15 lb | Tea Collection — 11 lb |
| 3-6M | 26 | 14.5–20 lb | 5.5 lb | Patagonia (baby) — 20 lb | Nike (infant/toddler) — 14.5 lb |
| 6-9M | 20 | 18–22 lb | 4 lb | The Children's Place — 22 lb | Primary — 18 lb |
| 6-12M * | 11 | 20–25 lb | 5 lb | Hatley — 25 lb | Hanna Andersson — 20 lb |
| 9-12M | 17 | 22–26 lb | 4 lb | The Children's Place — 26 lb | Walmart Garanimals — 22 lb |
| 12-18M | 26 | 24–28 lb | 4 lb | Carter's — 28 lb | Old Navy — 24 lb |
| 18-24M | 25 | 26–32 lb | 6 lb | Gerber Childrenswear — 32 lb | Old Navy — 26 lb |
| 2T | 16 | 28–33 lb | 5 lb | Gap (babyGap) — 33 lb | Old Navy — 28 lb |
| 3T | 18 | 32–36 lb | 4 lb | Gap (babyGap) — 36 lb | Old Navy — 32 lb |
| 4T | 17 | 36–40 lb | 4 lb | Gap (babyGap) — 40 lb | Old Navy — 36 lb |
| 5T | 14 | 41–48 lb | 7 lb | Hanna Andersson — 48 lb | Old Navy — 41 lb |
Each figure is a brand’s own published upper weight limit for that label, as printed on its size chart (retrieved September 2026). Where a brand prints a range, we use the top of the range. * “6–12M” is a single combined label some brands use instead of splitting 6–9M and 9–12M — itself part of why labels don’t line up. Charts published only in centimeters (H&M, Zara) are aligned by their stated age.
Whose labels cover heavier — or lighter — babies (on paper)
Averaged across every label a brand publishes, here is how far its upper weight limits sit above or below the cross-brand median. A plus sign means the label is printed to cover heavier babies; it is not a measurement of the garment, and not a fit guarantee. (A few sleepwear-focused brands size their charts on a different basis, so they sit out of this particular average.)
| Labels cover heavier babies (on paper) | Labels cover lighter babies (on paper) |
|---|---|
|
|
Deviation is the average of a brand’s published upper limits minus the cross-brand median at each label it covers. Small deviations (under ~half a pound) are within normal chart rounding.
The same baby, one label apart
The disagreement is big enough to shift a baby a whole size. The Children’s Place prints an upper limit of 22 lb for its 6–9M. Walmart’s Garanimals prints that same 22 lb as the top of its next label up (9–12M). A 21‑pound baby is a “6–9M” at one brand and a “9–12M” at the other — same child, two different tags. This is why the size that fit perfectly in one brand’s onesie can be too small in another’s.
A few charts have quietly become the standard
Not every brand invents its own numbers. Several publish the exact same grid: the Carter’s chart is also used by OshKosh B’gosh and Simple Joys; the Gap grid reappears at Colored Organics; H&M and Zara share the European centimeter grid (with different age labels on top); and the Kyte Baby grid is identical at KicKee Pants. When you match one of these, you’ve effectively matched several brands at once — but the moment you cross to a different grid, the pounds move again.
What this means when you shop
- Buy by weight and height, not the tag. Know your baby’s current numbers and read them against the specific brand’s chart — our Baby Clothing Size Index reconciles all 30 into one recommended chart, and the size calculator does the lookup for you.
- Check the chart every time you switch brands. Same tag, different pounds. The size charts by brand page puts them side by side.
- When in doubt, size up. A slightly big onesie gets worn for weeks; a snug one gets worn once. (A fit call, not a safety rule.)
- Shopping European sizes? Those are heights in centimeters, not ages — use the US / UK / EU converter so “size 80” doesn’t surprise you.
We read every brand’s size chart so you don’t have to. The Size Index reconciles all 30 into a single recommended weight-and-height chart.
See the Baby Clothing Size Index →How we built this
We collected the publicly published size charts of 30 baby-clothing brands (retrieved September 2026) — the same dataset behind our Baby Clothing Size Index — and, for each size label, recorded every brand’s printed upper weight limit. The “spread” is simply the lightest brand’s cutoff to the heaviest brand’s cutoff for that label. The “heavier / lighter on paper” averages compare each brand’s limits to the cross-brand median, and exclude a few sleepwear-focused charts that are built on a different sizing basis. We report only what the brands publish; we do not weigh garments or babies, and we make no fit guarantee.
Sources. Reconciled from the publicly published size charts of 30 brands (retrieved September 2026): Carter’s, OshKosh B’gosh, Gerber, Gap (babyGap), Old Navy, H&M, Zara, Target (Cat & Jack and Cloud Island), Walmart Garanimals, The Children’s Place, Hanna Andersson, Primary, Burt’s Bees Baby, Kyte Baby, Little Sleepies, Magnetic Me, KicKee Pants, Posh Peanut, Monica + Andy, Quincy Mae, Tea Collection, Janie and Jack, Nike, Amazon Essentials, Hudson Baby, Mini Boden, Hatley, Patagonia, L.L.Bean, and Colored Organics. Full per-brand chart links are listed in the Baby Clothing Size Index.
