Medically the review by Carissa Stephens, R.N., CCRN, CPN — created by MaryAnn De Pietro, CRT — updated on September 6, 2021

Weight is one indicator of an excellent nutrition and also physical development. That can therefore be helpful to know around babies’ average weight month by month.

You are watching: How much should my 9 month old weigh

First, the is worth noting that mean weight is not “normal” weight. As with adults, babies come in all shapes and sizes. If a baby’s weight is in a lower percentile, this does no necessarily signal a trouble with their development or physics development. Through this in mind, making use of a weight chart can help a person usually track your baby’s growth.

The Centers for an illness Control and also Prevention (CDC) recommend making use of the world Health company (WHO) weight chart for babies up to 2 year of age.

This short article describes the mean weight of a baby month by month native birth. It also explores what can affect a baby’s weight.

Average baby weights

Share top top PinterestMaskot/Getty Images
According to the WHO, the median birth weight of a full-term masculine baby is 7 pounds (lb) 6 ounces (oz), or 3.3 kilograms (kg). The average birth weight of a full-term mrs is 7 lb 2 oz, or 3.2 kg.

The average weight of a infant born at 37–40 weeks varieties from 5 lb 8 oz to 8 lb 13 oz. This is 2.5 to 4 kg. In ~ delivery, experts take into consideration a short birth load to be less than 5 lb 8 oz, or 2.5 kg.

It is usual for babies come lose approximately 10% of your weight soon after birth. This decrease is mostly due to fluid loss and also usually nothing to worry about. Many babies gain ago this weight within 1 week.

Baby load chart by age

Weight charts can assist a person tell what percentile their baby’s weight falls into. For example, if their weight is in the 60th percentile, it method that 40% the babies the the same age and also sex weigh more, and also 60% of this babies sweet less.

This does not necessarily typical that any kind of baby weighs too much or also little. It have the right to simply suggest where a baby’s weight drops on a spectrum.

The chart below shows infant weights in the 50th percentile. This is the typical weight. Masculine babies tend to weigh a little an ext than female babies, for this reason the chart is separated by 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)

What to expect

Babies grow and gain load the fastest in ~ the very first 6 month of life. Although this deserve to vary, babies have tendency to gain roughly 4–7 oz, or 113–200 grams (g), every week in the very first 4–6 months.

Weight acquire then slowly slightly, with an average obtain of roughly 3–5 oz (about 85–140 g) every week once the infant is 6–18 months. Top top average, babies triple your birth weight by their an initial birthday.

Growth patterns perform not monitor a clean schedule, however. Part babies gain weight steadily and stay in the very same percentile, or close to it, for several months. Others gain weight rapidly, signalling a growth spurt, i beg your pardon can happen at any time. This may move a baby into a new weight percentile.

What affects baby weight?

It is necessary not to emphasis on weight as the just indicator of physics development. Other dimensions of this advancement include the baby’s length and head circumference.

Considering all 3 measurements gives doctors an idea around how the baby is growing, contrasted with various other babies the the same age and sex.

Meanwhile, that is likewise important to keep various other developmental landmarks in mind. Assorted checklists of milestones by age are available, consisting of one indigenous, i beg your pardon is endorsed by organizations such as the American Academy of Pediatrics and the nationwide Association that Pediatric Nurse Practitioners.

For anyone looking for an ext information around what impacts the load of a baby, several factors can be involved, including:


Male newborns tend to be bigger 보다 female newborns, and they typically gain load a small faster during infancy.


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

The American Academy the Pediatrics notes that breastfed babies gain weight and grow much faster than formula-fed babies during the first 6 months.

However, that rate can shift during the next 6 months. Breastfed babies may get weight and grow more slowly 보다 formula-fed babies when they are aged 6 month to 1 year.

Medical conditions

Underlying health problems can reason a infant to gain weight an ext slowly. For example, babies v congenital heart irregularities may gain weight in ~ a slower rate than babies without this condition.

Health concerns that impact nutrient absorb or digestion, such together celiac disease, may likewise lead to slow weight gain.


Babies born prematurely might grow and also gain weight more slowly during their very first year than babies born at complete term.

However, numerous babies born prematurely obtain weight rapidly and also “catch up” by about their an initial birthday.

The mean birth load for full-term male babies is 7 lb 6 oz, or 3.3 kg. For female babies born full-term, the mean birth weight is 7 lb 2 oz, or 3.2 kg. Baby weight charts can aid a health care team monitor a baby’s physical development by comparing the baby’s weight v the weights of others of the exact same age and also sex.

Still, a doctor usually look at for steady growth, quite than a target percentile, as soon as assessing a baby’s physics development. And even if a baby’s weight is in a reduced percentile, they will not necessarily be a little adult — simply as longer babies execute not necessarily become tall adults.

Knowing around average weights through month can assist people gauge their babies’ physical development, however doctors likewise look for other vital indicators, such together length and also head circumference.

See more: How Much More Massive Is Jupiter Than Earth ? How Big Is Jupiter

Healthcare professionals likewise take right into account whether a baby is usually hitting other turning points on time. And by taking a comprehensive medical history, castle can dominion out any type of medical problems or nutritional considerations that might be avoiding a infant from obtaining weight appropriately.