Children develop at different paces, but the average birth weight of a full-term male baby is 3.3 kilograms (kg) and 3.2 kg for a female. Growth charts can provide a guide to the average weight of a baby.

First, it is worth noting that average weight is not typical weight. Just like adults, babies come in all shapes and sizes.

If a baby’s weight is in a lower percentile, this does not necessarily signal a problem with their growth or physical development. With this in mind, using a weight chart can help a person generally track their baby’s growth.

This article describes a baby’s average weight month by month from birth and explores what can affect it.

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The Centers for Disease Control and Prevention (CDC) recommends using the World Health Organization (WHO) weight chart for babies up to 2 years of age.

According to the WHO, the average birth weight of a full-term male baby is 7 pounds (lb) 6 ounces (oz), or 3.3 kilograms (kg). The average birth weight of a full-term female is 7 lb 2 oz, or 3.2 kg.

The average weight of a baby born at 37 to 40 weeks ranges from 5 lb 8 oz to 8 lb 13 oz. This equates to 2.5 to 4 kg.

At delivery, experts consider a low birth weight to be less than 5 lb 8 oz, or 2.5 kg.

It is common for babies to lose around 10% of their weight during the first week after birth. This decrease is mostly due to fluid loss and usually nothing to worry about. Most babies gain back this weight within 1 week.

Weight charts can help someone tell what percentile their baby’s weight falls into.

For example, if their weight is in the 60th percentile, 40% of babies of the same age and sex weigh more, and 60% of these babies weigh less.

This does not necessarily mean that any baby weighs too much or too little. It can simply indicate where a baby’s weight falls on a spectrum.

The chart below shows baby weights in the 50th percentile, which refers to the average weight. Male babies tend to weigh a little more than female babies, so the chart divides into sex.

Baby ageFemale 50th percentile weightMale 50th percentile weight
Birth7 lb 2 oz (3.2 kg)7 lb 6 oz (3.3 kg)
1 month9 lb 4 oz (4.2 kg)9 lb 14 oz (4.5 kg)
2 months11 lb 5 oz (5.1 kg)12 lb 4 oz (5.6 kg)
3 months12 lb 14 oz (5.8 kg)14 lb 1 oz (6.4 kg)
4 months14 lb 3 oz (6.4 kg)15 lb 7 oz (7.0 kg)
5 months15 lb 3 oz (6.9 kg)16 lb 9 oz (7.5 kg)
6 months16 lb 1 oz (7.3 kg)17 lb 8 oz (7.9 kg)
7 months16 lb 14 oz (7.6 kg)18 lb 5 oz (8.3 kg)
8 months17 lb 8 oz (7.9 kg)18 lb 15 oz (8.6 kg)
9 months18 lb 2 oz (8.2 kg)19 lb 10 oz (8.9 kg)
10 months18 lb 11 oz (8.5 kg)20 lb 3 oz (9.2 kg)
11 months19 lb 4 oz (8.7 kg)20 lb 12 oz (9.4 kg)
12 months19 lb 12 oz (8.9 kg)21 lb 4 oz (9.6 kg)

Babies usually gain weight most rapidly during the first 6 months of their life.

Typically, babies that are chest or breastfed gain weight slower in their first year than formula-fed infants.

It is common for babies to lose weight in their first week of life. They usually gain this weight back by the time they are 2 weeks old.

Although this can vary, babies tend to double their birth weight by the age of 4 months and usually weigh triple their birth weight by their first birthday.

However, growth patterns do not follow a clear schedule.

Some babies gain weight steadily and stay in the same percentile, or close to it, for several months.

Others gain weight rapidly, signaling a growth spurt, which can occur at any time. This may move a baby into a new weight percentile.

It is important not to focus on weight as the only indicator of physical development. Other measurements of this development include the baby’s length and head circumference.

Considering all three measurements gives doctors an idea about how the baby is growing, compared with other babies of the same age and sex.

Meanwhile, it is also important to consider other developmental milestones. Various checklists of milestones by age are available, including one from, which has endorsement from organizations such as the American Academy of Pediatrics (AAP) and the National Association of Pediatric Nurse Practitioners.

For anyone looking for more information about what influences the weight of a baby, several factors can have a role, including the following.


Male newborns tend to be bigger than female newborns and typically gain weight a little faster during infancy.


Weight gain and growth rates can also depend on whether the baby consumes breast milk or formula.

Chest or breastfed babies gain weight and grow slower than formula-fed babies during the first year.

However, growth generally follows a similar trend for both chest or breastfed and formula-fed babies.

Weight continues to fluctuate even after the baby starts eating other foods.

Medical conditions

Underlying health issues can cause a baby to gain weight more slowly. For example, babies with congenital heart irregularities may gain weight at a slower rate than babies without this condition.

Health issues that affect nutrient absorption or digestion, such as celiac disease, may also lead to slow weight gain.


Babies born prematurely may grow and gain weight more slowly during their first year than babies born at full term.

However, many premature babies gain weight rapidly and “catch up” by about their first birthday.

Below are some common questions about baby weight.

Is a 10-pound baby big?

According to the World Health Organisation (WHO), the average birth weight of a full-term male baby is 7 pounds lb 6 oz, and 7 lb 2 oz for a full-term female baby.

Therefore, a 10 lb baby is big compared to the average weight of a baby.

When should a baby double their birth weight?

Generally, a baby will weigh double their initial birth weight by the age of 4 months. They will usually weigh triple their birth weight by 12 months.

The average birth weight for full-term male babies is 7 pounds (lb) 6 ounces (oz), or 3.3 kilograms (kg). For female babies born full-term, the average birth weight is 7 lb 2 oz, or 3.2 kg.

Baby weight charts can help a healthcare team track a baby’s physical development by comparing the baby’s weight with that of an infant of the same age and sex.

Still, a doctor usually looks for steady growth rather than a target percentile when assessing a baby’s physical development. Even if a baby’s weight is in a lower percentile, it will not necessarily lead to them developing into a small adult, just as longer babies do not necessarily become tall adults.

Knowing about average weights by month can help people gauge their babies’ physical development, but doctors also look for other important indicators, such as length and head circumference.

Healthcare professionals also consider whether a baby is generally hitting other milestones on time. By taking a detailed medical history, they can rule out any medical conditions or nutritional considerations that may be preventing a baby from gaining weight appropriately.