Baby Clothes Size Finder
Baby clothes are labeled by age, but babies are not — and every brand draws its size chart differently. Enter your baby’s weight and this free tool shows the size whose typical range covers that weight (medians across 27 distinct published brand charts in our Size Index), how much brands disagree at that weight, and which labels run big or small. It reads brands’ own charts; it is not a measurement of your baby.
Quick answer: on the median of the brand charts in our Size Index, 0-3M fits about 8–12 lb, 3-6M about 12–17 lb, 6-9M about 16.5–20 lb and 12-18M about 22.5–27 lb. Enter the weight of your baby below to see the size for that weight and how far brands disagree.
Baby Clothes Size Finder
Enter your baby’s weight to see the size whose typical range covers it — and which brands run big or small. Typical ranges are medians across 27 distinct published brand size charts in our 30-brand Size Index (September 2026). It reads the brands’ own charts — it is not a measurement of your baby.
At 14 lb, the size whose typical range covers this weight is
3-6M
Even here brands vary: this label’s upper limit runs from 14.5 lb to 20 lb across the 28 brands that give a weight limit for it, so check the specific brand’s chart.
Runs small — size up
Old Navy, Hanna Andersson, Nike
Their label maxes out at a lighter weight on paper. This size-up tip is for daywear. For sleepwear and baby sleeping bags, choose the size shown for your child on the label.Runs big — size down
Patagonia, The Children’s Place, babyGap
Their label covers heavier babies on paper.Powered by Babbez · brand-published charts, Sept 2026 · we did not measure or test any garment.
How the size finder works
We compared the published size charts of 30 baby-clothing brands (27 distinct charts with weights) in September 2026. For any weight, the tool shows the size whose cross-brand median weight range contains it, the full range that weight spans across brands, and which brands’ charts run big or small. Every figure comes from the brands’ own charts — nothing here is estimated, and we did not measure or test any garment.
Why do baby-clothing sizes vary so much?
Because a size label is not standardized. On brands’ published charts the same “3–6M” label tops out anywhere from about 14.5 lb to 20 lb (28 brands print a 3–6M weight), and “18–24M” from about 26 lb to 32 lb (26 brands). That is why the same baby can wear two different labels depending on the brand — and why checking the specific brand’s chart beats trusting the label.
This tool is about clothing labels, not your baby’s growth or health. For your baby’s growth and the right time to move up a size, talk to your pediatrician and see the American Academy of Pediatrics. Read our medical disclaimer.
Size finder: common questions
How do I use the size finder?
Type the weight of your baby or drag the slider, choose lb or kg, and read the size whose typical range covers that weight. The line under the result shows how far brands disagree at that weight; if two sizes show, check the size chart of the brand you are buying.
What size fits my baby by weight?
On the median of the brand charts in our Size Index: Newborn about 6–8 lb, 0-3M 8–12 lb, 3-6M 12–17 lb, 6-9M 16.5–20 lb, 9-12M 20–23.5 lb, 12-18M 22.5–27 lb, 18-24M 27–30 lb, 2T 28.25–30.5 lb, 3T 31–34 lb and 4T 34–38 lb. The table below adds how far the top of each range varies across brands.
Why does the finder sometimes show two sizes?
Because the typical ranges overlap at some weights. At 16.5 to 17 lb, for example, a baby sits in both the 3-6M range (12–17 lb) and the 6-9M range (16.5–20 lb), so the right label depends on the brand.
Can I enter the weight in kilograms?
Yes. Switch the unit to kg: the finder converts the weight to pounds (1 kg is about 2.2 lb) and reads the same ranges.
Go deeper
- The Baby Clothing Size Index 2026 — the full 30-brand comparison behind this tool.
- The Sizing-Spread Index — how far the same label stretches across brands.
- What baby clothes really cost the first year — real per-item prices from 23 brands.
Baby and toddler clothing size by weight (from our 30-brand Size Index)
The finder above gives your baby’s brand-by-brand result. Here is the underlying reference in plain HTML: the typical weight range for each size, and how much the top of that range varies across the brands sold in the US whose published size charts we compared (the last column gives how many of the 30 print a weight for that size). Data from the Babbez Baby Clothing Size Index (September 2026); the same label is not the same size across brands, so treat these as approximate and buy by your baby’s measurement.
| Size | Typical weight range | Top of range varies (across brands) | Brands giving a weight limit |
|---|---|---|---|
| Preemie | up to 5.5 lb | 5–7 lb (2 lb spread) | 15 |
| Newborn | 6–8 lb | 7–10 lb (3 lb spread) | 27 |
| 0-3M | 8–12 lb | 11–15 lb (4 lb spread) | 27 |
| 3-6M | 12–17 lb | 14.5–20 lb (5.5 lb spread) | 28 |
| 6-9M | 16.5–20 lb | 18–22 lb (4 lb spread) | 22 |
| 9-12M | 20–23.5 lb | 22–26 lb (4 lb spread) | 18 |
| 12-18M | 22.5–27 lb | 24–28 lb (4 lb spread) | 28 |
| 18-24M | 27–30 lb | 26–32 lb (6 lb spread) | 26 |
| 2T | 28.25–30.5 lb | 28–33 lb (5 lb spread) | 18 |
| 3T | 31–34 lb | 32–36 lb (4 lb spread) | 19 |
| 4T | 34–38 lb | 36–40 lb (4 lb spread) | 17 |
| 5T | 38–42 lb | 41–46 lb (5 lb spread) | 13 |
Brands that tend to run big: Patagonia (baby) (+1.6 lb), The Children's Place (+1.3 lb), Gap (babyGap) (+1 lb), Mini Boden (+0.8 lb), Amazon Essentials (baby) (+0.7 lb), Hatley (+0.7 lb).
Brands that tend to run small: Old Navy (-1.4 lb), Hanna Andersson (-1.2 lb), Nike (infant/toddler) (-1.1 lb), Target Cat & Jack (-0.9 lb), Primary (-0.6 lb), Target Cloud Island (-0.6 lb), Walmart Garanimals (-0.5 lb).
Key findings (free to cite)
- The same '0-3M' label tops out anywhere from 11 lb to 15 lb across the 27 brands that print a 0-3M weight — a 4 lb spread.
- The same '3-6M' label tops out anywhere from 14.5 lb to 20 lb across the 28 brands that print a 3-6M weight — a 5.5 lb spread.
- The same '6-9M' label tops out anywhere from 18 lb to 22 lb across the 22 brands that print a 6-9M weight — a 4 lb spread.
- The same '9-12M' label tops out anywhere from 22 lb to 26 lb across the 18 brands that print a 9-12M weight — a 4 lb spread.
- The same '12-18M' label tops out anywhere from 24 lb to 28 lb across the 28 brands that print a 12-18M weight — a 4 lb spread.
- The same '18-24M' label tops out anywhere from 26 lb to 32 lb across the 26 brands that print an 18-24M weight — a 6 lb spread.
- The same '2T' label tops out anywhere from 28 lb to 33 lb across the 18 brands that publish a 2T weight limit — a 5 lb spread.
Source: Babbez Baby Clothing Size Index, 30 brands sold in the US, September 2026. Sizing information only, not medical or growth advice — see our medical disclaimer.