Should I size up for a baby?

For daywear, yes if the baby is between sizes and you want longer wear. For snug-fit sleepwear, stay at the labelled size.

Do sizes differ between brands?

Yes. Use the weight and height ranges as a guide and check the brand's own chart before buying.

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Baby and toddler clothing sizes by weight and height

Baby sizes are a guide, not a measurement. Brands cut differently, so use the chart below as a starting point and check the brand's own size chart before buying.

Size	Weight	Height
Newborn	up to 8–9 lb / 3.6–4.1 kg	up to 21 in / 53 cm
0–3 months	8–12 lb / 3.6–5.5 kg	21–24 in / 53–61 cm
3–6 months	12–17 lb / 5.5–7.7 kg	24–26 in / 61–66 cm
6–9 months	17–21 lb / 7.7–9.5 kg	26–28 in / 66–71 cm
9–12 months	21–25 lb / 9.5–11.3 kg	28–30 in / 71–76 cm
12–18 months	24–28 lb / 10.9–12.7 kg	30–32 in / 76–81 cm
18–24 months	27–30 lb / 12.2–13.6 kg	32–34 in / 81–86 cm
2T	29–32 lb / 13.2–14.5 kg	34–36 in / 86–91 cm

Between sizes?

For daywear, size up: cuffs can be rolled and babies grow fast. For snug-fit sleepwear, stay at the labelled size so the garment remains safely fitted to the skin.

What the labels don't say

Preemie and newborn clothes are quickly outgrown; buy only a few pieces until you know the birth weight.
Brands cut differently: Scandinavian brands tend to cut longer; French brands often cut slimmer.
Shrinkage happens: cotton items shrink 3–5% on the first wash unless pre-shrunk.

General guide only. Every baby is shaped differently.