Baby clothes sizing in the UK can be confusing — especially when you encounter European sizes like 80, 86, and 90 alongside UK age-based sizing. This complete baby clothes sizes UK guide covers everything you need to know, including a full size chart, how to measure your baby, and how UK sizing compares to European and US sizing.
UK Baby Clothes Size Chart
UK baby clothes are typically sized by age, but babies vary significantly in size. Always check the weight and height ranges alongside the age guide when choosing a size.
| UK Age Size | Height (cm) | Weight (kg) | EU Size |
|---|---|---|---|
| Newborn / First Size | Up to 56 cm | Up to 4 kg | 56 |
| 0–3 months | 56–62 cm | 4–6 kg | 62 |
| 3–6 months | 62–68 cm | 6–8 kg | 68 |
| 6–9 months | 68–74 cm | 8–9.5 kg | 74 |
| 9–12 months | 74–80 cm | 9.5–11 kg | 80 |
| 12–18 months | 80–86 cm | 11–13 kg | 86 |
| 18–24 months | 86–92 cm | 13–14.5 kg | 92 |
| 2–3 years | 92–98 cm | 14.5–16 kg | 98 |
| 3–4 years | 98–104 cm | 16–18 kg | 104 |
| 4–5 years | 104–110 cm | 18–20 kg | 110 |
| 5–6 years | 110–116 cm | 20–22 kg | 116 |
| 6–7 years | 116–122 cm | 22–25 kg | 122 |
| 7–8 years | 122–128 cm | 25–28 kg | 128 |
What is Size 90 in Baby Clothes?
Size 90 is a European baby clothes size that corresponds to a height of approximately 86–92 cm, which is typically worn by babies aged 18–24 months in the UK. If you are shopping for a baby who is around 1.5–2 years old and you see a garment labelled “size 90,” it should fit a child of that age and height range.
European sizing uses the child’s height in centimetres as the size number, which makes it more accurate than age-based sizing — two children of the same age can vary significantly in height and weight, so the EU system is often more reliable for getting the right fit.
What is Size 80 in Baby Clothes?
Size 80 corresponds to approximately 74–80 cm height, typically worn by babies aged 9–12 months in the UK. If you are shopping from a European brand and see size 80, it is equivalent to a UK 9–12 month size.
What is Size 86 in Baby Clothes?
Size 86 corresponds to approximately 80–86 cm height, typically worn by babies aged 12–18 months in the UK. This is one of the most commonly searched European baby sizes, as many popular Scandinavian and German baby brands use this sizing system.
How to Measure Your Baby for Clothes
The most accurate way to find the right size is to measure your baby’s height and weight and compare against the size chart above, rather than relying on age alone. Here is how to measure:
Height: Lay your baby on a flat surface. Use a soft tape measure to measure from the top of the head to the heel of the foot, keeping the baby as straight as possible. This is the most important measurement for sizing.
Weight: Use your baby’s most recent weight from a health visitor or GP appointment. Weight is a secondary guide — height is more reliable for clothing fit.
Chest: For older children (2+), measure around the fullest part of the chest, keeping the tape measure horizontal. This is useful for tops and dresses.
Should I Size Up?
For everyday clothing, buying one size up from your baby’s current measurements is a sensible approach — babies grow quickly, and a slightly larger size will last longer. For occasion wear such as christening outfits or party dresses that need to fit well on a specific day, buy to your baby’s current measurements rather than sizing up.
UK vs US Baby Clothes Sizes
US baby clothes sizing is similar to UK sizing in that it uses age ranges, but the age ranges do not always correspond exactly. US sizes tend to run slightly smaller than UK sizes at the younger end. As a general guide: US Newborn = UK Newborn, US 3M = UK 0–3 months, US 6M = UK 3–6 months, US 9M = UK 6–9 months, US 12M = UK 9–12 months.
Shop Baby Clothes in the Right Size at Itty Bitty
All products in our baby girl clothes range include detailed size guides with height and weight measurements. Browse our full collection of baby girl dresses, baby shoes, and kids boutique clothes — all with free UK delivery on orders over £50.