Baby Clothes Size Chart & Calculator

When I was expecting my first baby, I thought “newborn” was a one-size-fits-all label. Then my little one arrived two weeks early—and half of the tiny outfits I’d washed and folded were already too snug.
If you’ve ever stood in front of a rack wondering what size 70 or 0–3 months really means, you’re not alone. Baby clothing sizes can feel confusing, but once you spot the pattern, it all starts to make sense.

Our mission is to design clothes that last beyond a single growth spurt, so understanding sizing helps you buy smarter, waste less, and keep your baby comfortable through each stage.

Why Baby Clothing Sizes Feel So Confusing (Until You See the Pattern)

Most brands base baby sizes on average weight and length, but every baby grows at their own rhythm.
To make things trickier, UK labels often show age in months, while European brands use height in centimetres—that’s where those mysterious “size 68” or “size 80” numbers come from.

What I learned after two children:

• “Newborn” usually fits babies up to 3.4 kg / 7.5 lb or 50–56 cm tall.

• The next jump, “0–3 months,” covers roughly 56–62 cm.

• After that, European sizing takes over—each size is your baby’s height in centimetres.

So if your baby measures 70 cm head-to-toe, you’ll want size 70 clothes.

Baby Clothes Size Chart by Month (UK + EU Reference):

Age (approx.)	Height (cm)	Weight (kg)	EU Size	UK Label	Typical Fit
Newborn	45–50	2.5–3.4	50	Newborn	Tiny/first days
0–1 month	50–56	3.4–4.5	56	Up to 1 M	Most full-term newborns
0–3 months	56–62	4.5–6.0	62	0–3 M	Early growth stage
3–6 months	62–68	6.0–8.0	68	3–6 M	Rolling + first laughs
6–9 months	68–74	8.0–9.5	74	6–9 M	Sitting & crawling
9–12 months	74–80	9.5–10.5	80	9–12 M	Pulling to stand
12–18 months	80–86	10.5–12.0	86	12–18 M	First steps
18–24 months	86–92	12.0–13.5	92	18–24 M	Confident walking
2–3 years	92–98	13.5–15.5	98	2–3 Y	Toddler play

How to Use Our Baby Clothes Size Chart?

I created this size chart because I remember how confusing it felt to guess between newborn, 0–3 months, and size 68.
The chart above brings everything together in one place — age, height, and weight — so you can see at a glance which size fits your baby right now.

Here’s how I use it at home:

• Measure your baby’s height from the top of the head to the heel (barefoot).

• Check the weight range that matches your baby’s current stage.

• Compare both to the chart to find the best fit.

If your baby is between sizes or you’re buying for the months ahead, I always size up — babies grow faster than we think, and Aneby’s organic cotton stretches beautifully without losing shape.

Baby Clothes Size Calculator

 

Find Your Baby’s Size

Enter what you know — height gives the best match. Weight and age help fine-tune the fit and when to go up a size.

Height (cm)

Weight (kg) (optional)

Age (months) (optional)

Preferred fit True to size Room for layers Snug (sleepwear)

Show My Size Reset Why our fit lasts longer

Baby Clothing Sizes FAQs:

How do baby clothes sizes work?

Baby clothes sizes are based on your baby’s height and weight, not just age.

In the UK, sizes are often labelled in months (0–3M, 3–6M), while European brands use height in centimetres (like 62, 68, 74). 

For example, size 68 means the clothes are made for a baby who is around 68 cm tall.

What size is 80 in baby clothes?

Size 80 fits babies who are about 9–12 months old or roughly 74–80 cm tall.

In UK labels, it usually equals 9–12 M.

At this stage, most babies are crawling or beginning to stand, so look for flexible waistbands and comfy leg openings.

What is the difference between newborn and 0–3 month sizes?

Newborn clothes (size 50–56) fit babies under one month old, up to about 4.5 kg.

0–3 month clothes (size 62) are a little longer and roomier, perfect for the first growth spurt.

What size should I buy for a newborn baby?

Start with Size 56 if your baby weighs around 3–4 kg. Have a few Size 62 pieces ready — they’ll fit within weeks.

How long do babies wear newborn size?

Usually 1–3 weeks, depending on weight and length at birth.

What size comes after 80 in baby clothes?

Size 86, which fits most 12–18-month-olds or babies around 80–86 cm tall.

Are European baby sizes more accurate?

Yes, because they’re based on height rather than age, which varies less between babies.

Should I size up in baby clothes?

Yes, especially for gifts or fast-growing babies. Aneby’s relaxed fit and organic cotton adapt easily to growth.