# Baby Size Guide: Zara, H&M, Primark and International Brands
2.5 cm Monthly growth
3 months Duration per size
95% Reliability by height
Always use height as the primary reference for choosing a size, not age. Two babies of the same age can differ by up to 8–10 cm, which means jumping a full size.
# Sizes by age, height and weight
| Approx. age | Height (cm) | Weight (kg) | Usual size | Estimated use |
|---|---|---|---|---|
| Newborn | 50–56 | 3–4.5 | 50 / NB | 4–6 weeks |
| 1–3 months | 56–62 | 4.5–6 | 56–62 | 6–8 weeks |
| 3–6 months | 62–68 | 6–8 | 62–68 | 6–8 weeks |
| 6–9 months | 68–74 | 8–9.5 | 68–74 | 6–8 weeks |
| 9–12 months | 74–80 | 9.5–11 | 74–80 | 6–8 weeks |
| 12–18 months | 80–86 | 11–13 | 80–86 | 3–4 months |
| 18–24 months | 86–92 | 13–15 | 86–92 | 3–4 months |
# Brands that run large vs. slim
Run large (size down)
These brands use wider cuts; go one size smaller than usual.
- H&M: typically runs one size larger
- Primark: generally wide cut
- Lupilu (Lidl): loose fit overall
- Recommended for babies in lower percentiles
Run slim (size up)
These brands use narrower cuts; go one size larger than usual.
- Carter's: American slim cut
- Mayoral: fitted European cut
- Neck & Neck: reduced sizing
- Recommended for babies in higher percentiles
# Keys to getting the right size
- Always measure the baby before buying — do not rely solely on age
- If the result falls between two sizes, always choose the larger one
- Account for nappy room in bodysuits and all-in-ones
- European sizes (50, 56, 62...) correspond to height in cm
- Always wash before use: cotton can shrink up to 5%
- Size 50 / Newborn
- Designed for babies up to 50 cm tall and around 3.5 kg. Many babies outgrow it very quickly, even within the first weeks.
- Crotch length (rise)
- Distance from the crotch to the waist. Critical in bodysuits and rompers: a short rise restricts the baby's movement even if the rest of the garment fits well.
- Weight-based sizing
- American brands like Carter's use weight as the primary reference. Useful for babies with proportions outside the standard percentile.
- Envelope neckline
- Neckline design on bodysuits and T-shirts that allows dressing the baby by sliding the garment downward rather than over the head. Essential in the first months.
What to remember
Height is the most reliable indicator for choosing size, above age.
H&M and Primark tend to run large; Carter's and Mayoral run slim.
Numerical European sizes (50, 56, 62...) correspond to height in cm.
When between sizes, choosing the larger one ensures better durability.
Envelope necklines and a generous rise are the key comfort details.