First clothes are the part of the baby kit that people most often buy too much of, and in the wrong sizes. Yet size is not about age but about body length, and your baby will grow out of it faster than you expect.
In Slovakia and across continental Europe, baby clothes are labelled with a number that corresponds to body length in centimetres: 50, 56, 62, 68, 74 and so on, usually in steps of 6 cm. The European standard for clothing size designation states that for children the primary dimension is height, and for babies who are not yet standing, body length.3
The catch is that manufacturers read the number in different ways:
So it is more reliable to look at the particular maker’s size chart, or at the length range on the label, than at the age (“0–3 months”).
Enter your baby’s measured length. If you don’t know it, choose age and sex instead: we will use the median of the WHO growth standards, the value below which half of all children fall. Your own child may well be shorter or longer.
Enter a length or an age and we will show which size fits now and which comes next.
The WHO growth standards show the median length, the value below which half of all healthy children fall.1,2
| Age | Girls (median) | Boys (median) | Size, reading it as “middle of range” |
|---|---|---|---|
| at birth | 49.1 cm | 49.9 cm | 50 |
| 1 month | 53.7 cm | 54.7 cm | 56 |
| 2 months | 57.1 cm | 58.4 cm | 56 |
| 3 months | 59.8 cm | 61.4 cm | 62 |
| 4 months | 62.1 cm | 63.9 cm | 62 |
| 6 months | 65.7 cm | 67.6 cm | 68 |
| 9 months | 70.1 cm | 72.0 cm | 68–74 |
| 12 months | 74.0 cm | 75.7 cm | 74 |
Half of all children are longer, half shorter. For a baby who is already long at birth, size 50 may not be worth buying at all.
Length at birth and at check-ups is measured by the paediatrician; you will find that figure in the health record. If you want a rough measurement at home, lay your baby on their back on a flat surface and, with a second person helping, measure from the top of the head to the heel with the leg gently straightened. Home measurements tend to be a centimetre or two out, which is fine for choosing a size.
The table below is our editorial estimate for the first weeks, not a recommendation from a health authority. Adjust it to how often you do the washing and to the season.
| Item | Size 50–56 | Size 62 | Note |
|---|---|---|---|
| Short- or long-sleeved bodysuits | 4–6 | 4–6 | poppers at the crotch |
| Sleepsuits or rompers | 4–6 | 4–6 | fastening at the front or side |
| Socks or booties | 3–4 pairs | 3–4 pairs | |
| Hat | 1–2 | 1 | for outdoors; no hat needed indoors4 |
| A warmer layer (cardigan, little hoodie) | 1–2 | 1–2 | |
| Snowsuit or warm all-in-one | depending on the season | depending on the season | the NHS lists one for the hospital bag if it is cold5 |
| Scratch mitts | 1–2 pairs | — | optional |
Cotton is practical for babies: it breathes and stands up to frequent washing. For winter, fine wool or merino works well as a layer. With synthetic fabrics, watch whether your baby gets sweaty.
The Lullaby Trust recommends dressing your baby in layers that can be added or taken off, and checking their temperature on the tummy, back or back of the neck. Do not put a hat on indoors; the head helps to let heat out.4 More in the article Dressing your baby for the temperature.
Many newborns measure around 50 cm at birth; the WHO median is 49.1 cm for girls and 49.9 cm for boys. Most families therefore go for size 50 or 56. An item in size 56 is the safer choice if you don’t want to risk it being too small.
According to the WHO median, a baby measures around 54 cm at one month and around 57–58 cm at two months. Individual children vary a great deal, so there is no need to buy lots of items in one small size.
Most parents wash new clothes before the first wear, to remove residues from manufacturing and soften the fabric. Follow the care label.
The numbers in the text refer to these sources. The links go to the publishers’ own pages; we simply cite them.
We last checked these sources on 13 October 2026.
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