The ideal weight of new born baby at full term is usually between 2.5 and 4 kg. The WHO median, the middle value for healthy babies, is 3.3 kg for boys and 3.2 kg for girls. Many healthy Indian babies are born a little lighter than that, often around 2.8 to 3 kg.
A baby below 2.5 kg is called low birth weight and needs closer care in the first weeks. A baby above 4 kg is called large for dates; this can follow diabetes in pregnancy and needs some checks after birth.
Quick numbers
Normal birth weight
2.5 to 4 kgWHO median, boys
3.3 kgWHO median, girls
3.2 kgLow birth weight
under 2.5 kgBack to birth weight
by 10 to 14 days
Ideal weight of new born baby by category
| Birth weight | What it is called | What it usually means |
|---|---|---|
| Under 1.5 kg | Very low birth weight | Often premature; special newborn care |
| 1.5 to 2.49 kg | Low birth weight | Extra feeding support and warmth |
| 2.5 to 4 kg | Normal | Routine newborn care |
| Over 4 kg | Large baby | Check blood sugar and birth injuries |
Category labels guide care; they are not grades. Many small babies catch up quickly with good feeding.
Ideal weight for new born baby boy and girl
Baby boys are on average 100 to 200 g heavier at birth than girls. WHO standards place the middle 95 percent of healthy full-term boys between about 2.5 and 4.4 kg and girls between about 2.4 and 4.2 kg. A healthy baby anywhere in that span is normal.
What affects birth weight
- How many weeks the pregnancy lasted; every week near term adds roughly 150 to 200 g.
- The mother's own height, weight and weight gain in pregnancy.
- Nutrition, anaemia and blood pressure during pregnancy.
- Twins and triplets, who are usually lighter.
- Smoking and tobacco use, which lower birth weight.
- Diabetes in pregnancy, which can raise it.
Good care in pregnancy, from iron and folic acid to healthy weight gain, supports a healthy birth weight. See the pregnancy weight gain guide.
The first two weeks
Almost all newborns lose some weight after birth, often 5 to 7 percent and up to about 10 percent, as they pass fluid and learn to feed. A 3 kg baby may drop to about 2.75 kg by day 3 or 4. Most are back to birth weight by 10 to 14 days and then put on roughly 20 to 30 g a day.
Feeding often, eight to twelve times a day for breastfed babies, helps this happen. Plenty of wet nappies, at least six daily from the second week, shows the baby is getting enough milk.
Low birth weight babies
Small babies lose heat easily and may tire while feeding. Skin-to-skin contact, known as kangaroo mother care, keeps them warm and helps breastfeeding. Frequent feeds, weight checks and follow-up visits are part of the plan. Most low birth weight babies who are otherwise well grow steadily and catch up over the first year.
After the newborn period
From two weeks on, follow the month by month numbers on the baby weight chart. After the first birthday, the kids weight by age page takes over. For why BMI is not used for babies, see the child BMI page.
Call your paediatrician or go to hospital if a newborn feeds poorly, is very sleepy or hard to wake, has a yellow colour spreading to the tummy or legs, has fever, or seems to pass little urine once the first week is over.
Measuring at home
Home scales are not accurate enough for newborn changes of 20 to 30 g a day. Rely on clinic weights during the first weeks, ideally on the same scale each time.
Frequently asked questions
What is the ideal weight of new born baby?
Between 2.5 and 4 kg at full term, with a WHO median of 3.3 kg for boys and 3.2 kg for girls.
What is the ideal birth weight of a baby in India?
The same normal range of 2.5 to 4 kg applies. Many Indian babies are born around 2.8 to 3 kg and are healthy.
Is 2.5 kg a normal birth weight?
It is at the lower edge of normal. Babies under 2.5 kg are called low birth weight and get closer follow-up.
How much weight does a newborn lose after birth?
Usually 5 to 7 percent and up to about 10 percent in the first few days, regained by 10 to 14 days.
Is a 4 kg baby too big?
A baby over 4 kg is called large. Most are healthy, but doctors check blood sugar and look for birth injuries.
How much should a newborn gain in a week?
Roughly 20 to 30 g a day, once birth weight is back.
Sources
- WHO Child Growth Standards
- World Health Organization definitions of low birth weight