Baby clothes sizes: how to get a gift right

On European-sized clothing, the number on the label is not age or weight but the maximum body length the piece is made for. Size 62 therefore fits a child measuring up to about 62 cm, and covers everything from roughly 57 cm. This comes from the European standard EN 13402, under which children's clothing is labelled by body height.

The age that shops print next to the size (say, “2–4 months”) is just a conversion based on an average child. According to the WHO growth standards, an average boy is about 61 cm long at three months and around 76 cm at one year, with girls a centimetre or two shorter. Any particular child can easily differ from the average by a whole size, in either direction.

Two more practical points: a double label such as 62/68 means the piece will last across both sizes (it tends to be roomier or has a turn-up cuff), and cotton shrinks a little after its first hot wash. Cuts also vary from brand to brand – with some makers, a 68 runs narrow and short.

A sweet little all-in-one in size 50 is the most common gift that ends up in a box with the tag still on. There are four reasons for that.

Babies are born right at the edge of it. The average newborn is around 50 cm long, so half of all babies are bigger from day one than size 50 is made for. And babies grow fastest in the first weeks – according to the WHO growth curves, they gain roughly 4 cm a month in the first two months.

Everyone gives it. A gift “for the birth” tempts people towards the smallest size, because it looks the cutest. Parents then end up with ten pieces in size 50 and only a few weeks to wear them.

The first weeks are all about comfort. A baby gets changed several times a day, so at home it is bodysuits, rompers and zip-up onesies that win. Little dresses with buttons down the back or a tiny shirt hardly ever get a turn in the first six weeks.

The season is wrong. A thick padded suit in size 56 for a baby born as the warm months begin will go unused, because by the time the cold weather arrives the baby will be three sizes further on.

Size 44 is made for premature babies, who are born smaller and lighter. You usually won't find it in ordinary shops, and it doesn't belong in the layette for a full-term baby – even a smaller newborn will probably wear it for just a few days.

If the baby arrived early, though, this is exactly the gift the parents don't have: they weren't expecting the baby so soon, and an ordinary size 50 is too big. Ask first what they need – hospitals often have rules about what premature babies may wear, and front openings and soft seams matter more than looks.

A rough layette for a full-term baby for the first three months. The numbers of pieces are a sensible base, not a must – it depends on how often you do the washing.

Clothes are the gift most likely to miss, because you are aiming at a number that changes every month. When in doubt, stick to the rule “two sizes up from what the baby wears now”, or choose a gift that doesn't depend on size at all. Tips on how to share out new baby gifts with others are in the article Gifts for a new baby: three piles and what goes where, and for a christening or naming ceremony in Christening gifts: who gives what and how to avoid doubling up.

If you want to give something the child won't outgrow in a month, it could be a personalised book in which the child, based on a photo, becomes the hero. For a baby it is more of a gift for later – it makes sense once they can listen to a story, perhaps for a first birthday.