Baby & Kids' Clothing Size Chart by Age

Why age-based sizing isn't exact

Baby and kids' clothing is usually labelled by age (e.g. 6–9 months, 2–3 years), but babies of the same age can vary a lot in height and weight. When buying preloved, the age on the label is a starting point, not a guarantee of fit — always check the seller's listed measurements or ask for them if they're not given.

Age-to-size chart

• Newborn (0–3 months) — up to ~60 cm / 3–6 kg.
• 3–6 months — ~60–67 cm / 6–8 kg.
• 6–9 months — ~67–72 cm / 8–9 kg.
• 9–12 months — ~72–80 cm / 9–10.5 kg.
• 12–18 months — ~80–86 cm / 10.5–12 kg.
• 18–24 months — ~86–92 cm / 12–13.5 kg.
• 2–3 years — ~92–98 cm / 13.5–15.5 kg.
• 3–4 years — ~98–104 cm / 15.5–17.5 kg.
• 4–5 years — ~104–110 cm / 17.5–19.5 kg.

Sizing tips when buying preloved

• If your child is tall or heavy for their age, size up rather than going by age alone.
• Ask the seller for the brand and size label, not just the age range — sizing varies between brands.
• For fast-growing age ranges (0–12 months), buy slightly ahead of your child's current age.
• Check the fabric — knits and stretch fabrics are more forgiving of small size mismatches than woven fabrics.