Baby weight and height can vary more than many parents expect. When your baby is born it is completely natural to wonder how they compare with other babies. This guide explains typical baby weight and growth patterns in the UK so you can understand what is normal and what health visitors usually look for.
Quick summary
Many parents look for a simple answer when they first start thinking about baby growth. The key things to know are:
- The average birth weight in the UK is around 3.3–3.5 kg (7 lb 4 oz to 7 lb 11 oz) for full‑term babies
- Most healthy newborns weigh between 2.5 kg and 4 kg
- Babies usually lose a small amount of weight after birth and regain it within two weeks
- Growth is tracked using centile charts in the red book rather than a single “ideal weight”
This article is for / not for
This article is for:
- Parents who want a clearer understanding of typical baby weight in the UK
- Parents wondering whether their baby’s growth seems normal
- Anyone who has heard numbers mentioned by health visitors and wants to understand what they actually mean
This article is not for:
- Situations where a baby needs urgent medical advice
- Parents seeking diagnosis about feeding or health concerns
In those cases a health visitor, GP, or midwife should always be the first point of contact.
Medical disclaimer
This article provides general information about baby growth patterns in the UK. It cannot diagnose health or feeding concerns. If you are worried about your baby’s weight or growth, speak to your health visitor, GP, or midwife, or refer to guidance from the NHS.
Average baby weight at birth
The average newborn weight for boys and girls in the UK is around 7.5 lb (3.4 kg).
However, newborn weights naturally vary quite a lot. Around half of babies are born between 5 lb (2.26 kg) and 8 lb (3.62 kg). Some babies are smaller and some are larger, and both can still be completely healthy.
Newborn boys tend to be slightly heavier than newborn girls, although the difference is small. On average the gap is roughly 0.2 lb (about 90 g).
What matters far more than the number at birth is how a baby grows over time.
What is the average birth weight in the UK?
The average birth weight in the UK is around 3.3–3.5 kg (7 lb 4 oz to 7 lb 11 oz) for babies born at full term.
Doctors usually describe newborn weights in ranges rather than focusing on a single number. Babies weighing below 2.5 kg are described as low birth weight, while babies between 2.5 kg and 4 kg fall within the typical range for full‑term births. Babies above 4 kg are sometimes described as larger than average.
Even so, health visitors rarely focus on a single number alone. What they are really looking for is whether a baby continues to grow steadily over time.
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How baby growth charts work
In the UK, health professionals use the UK‑WHO growth charts. These charts are included in your baby’s Personal Child Health Record, often called the red book.
The curved lines on the chart are called centiles. They show how a baby’s growth compares with other babies of the same age and sex.
For example, a baby on the 50th centile sits right in the middle of the growth range. A baby on the 25th centile is smaller than average but still well within a healthy range, while a baby on the 75th centile is slightly larger than average.
Health visitors are usually less concerned about the exact centile and more interested in whether a baby continues along a similar growth line over time.
How much weight should a baby gain each month?
Many parents are surprised to learn that babies often lose a little weight during the first few days after birth. This is completely normal and usually reflects fluid loss and early feeding adjustments.
Most babies lose around 5–10% of their birth weight during this short period.
Within about 10 to 14 days, babies typically regain that weight. Health visitors often check weight during this time simply to make sure feeding is going smoothly.
After this early stage, babies tend to gain weight quite quickly during the first few months. In general, babies may gain roughly 4–7 ounces (110–200 g) per week during the early months, although every baby grows at their own pace.
Growth often slows a little later in the first year as babies become more active, start rolling, and eventually begin crawling.
Breastfed vs formula‑fed babies
Parents sometimes notice small differences in growth patterns between breastfed and formula‑fed babies.
Breastfed babies may gain weight slightly more slowly after the early months. This is usually considered completely normal and does not mean anything is wrong.
Part of the reason may be feeding style. Babies feeding directly from the breast often stop when they feel satisfied, while bottle‑fed babies may occasionally drink a little more.
Both feeding approaches can support healthy growth when babies are feeding well and gaining weight steadily.
When babies regain their birth weight
Most babies return to their birth weight within 10 to 14 days after being born.
Health visitors often weigh babies during this period simply to check that feeding is going well and that growth is moving in the right direction.
If weight takes slightly longer to return to birth weight, professionals will usually just monitor feeding and growth for a little longer.
When babies usually double their birth weight
A common rule many parents hear is that babies often double their birth weight by around four to six months, and triple their birth weight by their first birthday.
These milestones are only general patterns rather than strict targets. Some babies grow faster while others grow more gradually, and both can be completely healthy.
Again, what health visitors tend to focus on most is steady growth over time.
Baby weight and height changes in the first year
The first year of life is a period of very rapid growth.
During these months babies usually gain weight quickly, particularly in the first six months. Growth then tends to slow slightly between six and twelve months as babies become more mobile.
At the same time, babies grow longer and their head circumference increases as their brain develops.
Because every baby develops differently, health professionals rely on centile charts rather than fixed targets.
When to speak to a health visitor about baby weight
Most differences in baby weight are completely normal. Parents often worry when their baby appears smaller or larger than another baby, but growth can vary widely.
However, it can be helpful to speak to a health visitor if a baby has not regained their birth weight after around two weeks, if growth appears to drop across several centile lines, or if feeding difficulties seem to be affecting weight gain.
In practice, health professionals look at the overall growth picture, rather than focusing on one measurement.
Average baby weight and height/ length for babies
The tables below show the average baby weight and height for their age up to 12 months. We made these tables as it makes easier reading than the centile charts. You can download and print those off below. Remember these are only averages and your baby may fall two or three pounds/cm on either side of these figures.
Fifty percent of babies fall within the 25th and 75th centiles in the charts. Always talk to your health visitor or doctor if you are concerened about your baby’s weight.
Baby girl and baby boy growth charts
Here are the WHO Baby growth charts for boys and girls. These charts cover your babies weight, height/ length and head circumference. You can find out where your baby lies on the centile charts from birth to 4 years old. These are the same charts as in the Redbook.
You may want to download and print them and add them to a keepsake book. Remember you can download the eRedbook to keep your baby’s details in. Click or tap the images to download.
Some amazing baby weight and height facts
The Heaviest baby
According to Guinness World Records, the heaviest baby to be born was to Sig. Carmelina Fedele at Aversa, Italy in September 1955. She had a boy who weighed in at an eye-watering 22 lb 8 oz (10.2 kg).
For reference that’s over three times the weight of an average baby boy born in the UK today. Or just over the combined weight of 23 large lattes at Costa.
The longest baby
‘Babe’ is the record holder as the longest baby ever born. He was born in Canada on 19th January 1879. ‘Babe’ died 11 hours after being born. He was never given an actual name.
When ‘Babe’ was born, he measured 2ft 4 in (71.12cm). He weighed in at 22lbs (9.98kg). His mother was Anna Bates who was pretty tall too, she was a towering 7ft 11in (241.3cm). ‘Babe’ was born at her home in Ohio, USA.
The heaviest babies born in the UK
The heaviest baby ever born in the UK was 15lb 8oz Guy Carr, from Barrow-in-Furness, Cumbria, in 1992. Guy was delivered by Caesarean section.
The heaviest baby born naturally in the UK was on 11th February 2013 to Jade Packer. Her baby George weighed in at 15lbs 7oz. He was born at Gloucester Royal Infirmary and was 2 weeks late.
Speaking about the birth Jade said ‘It wasn’t very dignified’. ‘I vaguely remember having my legs up near my head and loads of people trying to pull and push him out. There were about 20 people in the room all helping and rushing about.’
The Heaviest girl at birth was born to Elaine Martin and Sean O’Halloran in 2012. Niamh was near twice the average, weighing in at 14lb 4oz. Her birth weight was even off the scale for the charts in the redbook.
You may like to read these next
- What helps when nothing settles your baby looks at those exhausting moments when a baby seems impossible to soothe. It explores practical, gentle things parents sometimes find helpful when feeding, rocking, or usual routines just are not working.
- Baby growth: 28 amazing baby milestones covers the milestones babies pass in the first 12 months
External guidance
If you would like to explore official guidance, these UK sources can also help:
What to take away
Most babies grow in their own unique pattern.
It is completely natural for parents to compare numbers and wonder whether their baby is “average”. In reality, doctors and health visitors focus much more on steady growth over time.
If your baby is feeding well, gaining weight gradually, and following their own growth pattern, that is usually a reassuring sign that things are progressing normally.