Baby Clothing Size Calculator
Stop guessing (and stop returning). Enter your baby's age, weight, or height and get the right clothing size in seconds — plus how much growing room to leave.
See the full size chart (age · weight · height)
| Size | Age | Weight (lb) | Height (in) |
|---|
This calculator gives general sizing guidance to help you shop and reduce returns — it is not medical or growth advice. See our full medical disclaimer. Every baby grows differently and clothing sizes vary between brands; when in doubt, size up for comfort and longer wear. Data reflects standard US baby & toddler apparel sizing.
Baby clothing sizes — FAQ
How do I know what size clothes my baby needs?
Go by your baby’s current weight and height rather than the age on the label — babies vary a lot and brands differ. Enter all three here and the calculator suggests the best-fit size.
What size should I buy for a newborn?
Buy light on the newborn size; many babies wear it only a week or two, and larger newborns may go straight into 0–3M. Keep the tags on so you can exchange.
More size help: baby clothes sizes by age (the complete guide) · why sizes run different by brand · shop baby clothing by size
Quick-reference size chart
| Size | Age | Weight | Height |
|---|---|---|---|
| Preemie | preemie | up to 6 lb | up to 17" |
| Newborn | up to 1 month | 6–9 lb | 17–21.5" |
| 0–3M | 1–3 months | 9–12.5 lb | 21.5–24" |
| 3–6M | 3–6 months | 12.5–17 lb | 24–26.5" |
| 6–9M | 6–9 months | 17–21 lb | 26.5–28.5" |
| 9–12M | 9–12 months | 21–25 lb | 28.5–30.5" |
| 12–18M | 12–18 months | 25–28 lb | 30.5–32.5" |
| 18–24M | 18–24 months | 28–30 lb | 32.5–34" |
| 2T | 24–36 months | 30–33 lb | 34–36" |
| 3T | 36–48 months | 33–36 lb | 36–38.5" |
| 4T | 48–60 months | 36–40 lb | 38.5–41" |
Standard US baby & toddler apparel sizing — the same bands the calculator above uses.