The baby size guide

Help, baby's on the way and I don't understand anything about sizes! Which clothing size should you choose for baby's arrival?

Afraid of buying too small, afraid that baby will be swimming in their clothes… Finding the right size isn't as easy as it seems! But don't worry, we'll show you all the pitfalls to avoid with our baby size guide!

Pitfall no. 1: The clothing size doesn't match the baby's age!

Whatever our age, the sizes shown on our clothes are never straightforward: a 10-year-old child never wears age 10… just as your feet don’t measure 38 cm if you’re a size 38!
Well, it’s the same for babies! Most babies, for example, will wear size 1 month from their very first days.

To choose the right baby clothes, go by your baby’s height and weight rather than their exact age.

And to help you see things more clearly, here's a rough guide to which size to choose for baby's clothes:

Age	Weight	Height (up to)
Premature	Up to 2.5kg	45 cm
Newborn	From 2.5 to 3.3kg	50 cm
1 month	From 3.3 to 4kg	54 cm
3 months	From 4 to 6 kg	60 cm
6 months	From 6 to 8 kg	67 cm
9 months	From 8 to 9 kg	71 cm
12 months	From 9 to 10 kg	74 cm
18 months	Not applicable	81 cm
24 months		86 cm
36 months		94 cm

Don’t overdo newborn size! Newborn size will only fit your baby if they weigh no more than 3.3 kg and measure under 50 cm. And many babies never wear newborn size at all.
So here’s our advice: for a baby sleepsuit or a bodysuit, go for 1-month size (up to 4 kg and 54 cm) to be sure baby is comfortable. But don’t go too far the other way either by putting them in 3-month size from birth: that’s far too big! 3-month size generally fits babies weighing between 4 and 6 kg and measuring around 60 cm.

So bear in mind that the age shown on clothes doesn't match your baby's age! Depending on their build, a newborn may wear 1 month size, a 1-month-old baby 3 months size, and so on!

Pitfall no. 2: Don't buy your clothes too early!

Indeed, wait for your third scan before choosing the size of baby's clothes: your sonographer will give you an idea of your baby's weight and length, which will help you choose the most suitable sizes.

If you're expecting a small baby: still buy mostly 1 month size and add a few newborn-size clothes. That should be enough. Baby will grow quickly… very quickly, too quickly!

To give you an idea, the average baby measures around 50 cm and weighs 3.2 kg. And the vast majority of babies measure between 46 and 54 cm and weigh between 2.4 and 4.2 kg (hence our advice to go for 1 month)!

Pitfall no. 3: Before giving a baby gift, think about the seasons!

On that note, if it's a gift, don't give newborn size! Choose 1 or 3 months, and don't hesitate to simply ask the parents-to-be what they prefer! And if you want to give larger sizes, think about the changing seasons! Don't give a big, warm coat in 6 months size to a baby born in the middle of winter. Unless the family is planning a summer trip to the North Pole, there's little chance baby will ever wear it. On the other hand, a lovely summer outfit, why not?

What clothes should you pack for the day of the birth?

100% cotton bodysuits and sleepsuits that open at the front, a going-home outfit, first baths: read our advice article on all the essentials to plan for the day of the birth!

Dylan
Proud dad of three little ones and founder of Premiers Moments. Together with the whole team, I share our parenting tips here to support you, from pregnancy through your child's first years.