Average Height and Weight for Kids by Age – Growth Charts

Children in the United States grow at predictable rates tracked by the CDC. A newborn averages 7.5 lbs and 20 inches at birth; the average 18-year-old boy stands 5 feet 9 inches and the average 18-year-old girl stands 5 feet 4 inches. These numbers shift predictably year by year, and knowing what is typical helps parents catch patterns worth reviewing with a pediatrician.

Newborn to 12 Months: What Babies Weigh and Measure at Birth Through Year One

Newborns average 7.5 pounds (3.4 kg) and 20 inches (50.8 cm) at birth, with most healthy babies falling between 5.5 lbs and 10 lbs. Babies are expected to double their birth weight by 5 months and triple it by 12 months, making weight the most closely watched number in the first year.

By 12 months, the average boy weighs 21.3 lbs (9.6 kg) and stands 29.8 inches (75.7 cm). The average girl at 12 months weighs 19.6 lbs (8.9 kg) and stands 29.2 inches (74.0 cm). Most babies grow 10 inches (25 cm) between birth and their first birthday.

Head circumference is measured at every well-child visit during the first two years. The average at birth is 13.8 inches (35 cm), rising to roughly 18 inches (45.7 cm) by 12 months. Pediatricians track head measurements to monitor brain development alongside body growth.

Toddler Growth from Age 1 to 2: Why Weight Gain Slows Dramatically

Between ages 1 and 2, most toddlers gain only 4 to 6 lbs and grow 3 to 4 inches, a sharp deceleration from the pace of infancy. This slowdown is biologically normal and is the reason toddler appetites drop noticeably compared to the first year.

By 24 months, the average boy weighs 27.5 lbs (12.5 kg) and stands 34.2 inches (86.8 cm). The average 2-year-old girl weighs 26.5 lbs (12.0 kg) and stands 33.9 inches (86.0 cm). A well-established pediatric rule: height at age 2 is approximately half the child’s eventual adult height.

Pediatricians use growth percentile curves (rankings that place a child relative to 100 peers of the same age and sex) rather than single weight snapshots to evaluate whether a child is developing on track. A child who consistently tracks at the same percentile across visits is considered to be growing normally, regardless of where that percentile falls.

Preschool Years, Ages 2 to 5: Steady and Predictable Gains Every Year

Children between 2 and 5 years grow approximately 2 to 2.5 inches per year and gain around 4 to 5 lbs per year, making this one of the most consistent and predictable growth phases. Growth velocity (the rate of growth per year) remains essentially constant throughout the preschool window.

Boys and girls are nearly identical in height and weight at every preschool age, with differences of less than 1 inch and 1 pound at most checkpoints. This near-parity holds until hormonal changes in puberty begin to separate the sexes.

BMI-for-age (body mass index for age), which compares a child’s weight-to-height ratio against age and sex-specific CDC percentile charts, is formally tracked starting at age 2. A BMI-for-age between the 5th and 84th percentile is considered healthy for children aged 2 and older.

Middle Childhood, Ages 5 to 8: Two Inches Per Year Like Clockwork

Children aged 5 to 8 years grow at approximately 2 inches per year in height and gain 4 to 6 lbs per year in weight, producing one of the most reliable and predictable growth rates across all childhood age groups. Most parents notice clothing and shoe sizes needing an upgrade on a consistent annual cycle during these years.

By age 8, the average boy stands 50.4 inches (4 feet 2 inches) and the average girl stands 50.2 inches, a difference of under half an inch. Weight is similarly close, with boys averaging only about 1 pound more than girls at this age.

This calculator automatically adjusts for differences in height, age and gender, calculating a child’s height percentile along with blood pressure percentile.

Physical size and motor ability do not always track together during middle childhood. A smaller child may have significantly more advanced coordination than a larger same-age peer. Growth charts capture body dimensions only, not developmental capability or school readiness.

Why Girls Outgrow Boys Between Ages 8 and 11

By age 10, the average girl is measurably taller and heavier than the average boy of the same age, a reversal that results from girls entering puberty earlier than boys. This shift typically becomes detectable in growth data between ages 9 and 11.

The pubertal growth spurt (the surge in height and weight caused by rising hormones at the start of puberty) begins in most girls between ages 8 and 13, with peak velocity around age 11 to 12. Boys begin the same spurt later, typically between ages 10 and 14, with peak velocity around age 13 to 14.

During the growth spurt, girls can gain 2 to 3 inches per year instead of the usual 2. Weight gain accelerates simultaneously due to increases in bone density and body fat. A girl who appears noticeably bigger between two consecutive school years is experiencing a normal hormonal growth response.

Puberty’s Impact on Growth, Ages 11 to 14: The Highest-Variation Window

Ages 11 to 14 represent the most variable growth period in all of childhood, during which two 12-year-old boys of identical age can differ by 5 inches and 30 pounds while both remaining completely healthy. Comparing children to one another by age is least useful during this phase; tracking a child’s own curve over time is far more meaningful.

By age 14, boys have overtaken girls in both height and weight. The average 14-year-old boy stands 64.5 inches (5 feet 4.5 inches) and weighs 112 lbs, while the average 14-year-old girl stands 62.5 inches (5 feet 2.5 inches) and weighs 107 lbs.

Tanner stages (a clinical scale from 1 to 5 describing the physical progression of puberty based on observable body changes) are used by pediatricians alongside height and weight data to determine whether a child’s development is proceeding normally. Growth charts alone cannot show where a child is in the puberty process.

Teen Growth from 14 to 18: When Boys Catch Up and Girls Level Off

By age 14 to 15, most girls have completed their pubertal growth spurt and gain very little additional height after this point. Boys continue meaningful height growth through age 16 to 17, and some add small amounts into their early 20s before growth plates close permanently.

The average 18-year-old American male stands 5 feet 9 inches (69.2 inches) and weighs 148 lbs. The average 18-year-old American female stands 5 feet 4 inches (64 inches) and weighs 126.5 lbs. These figures are consistent with CDC data and National Health and Nutrition Examination Survey (NHANES) findings from population-level sampling.

Most girls reach 95% of their adult height by age 16 and their full height by age 18. Most boys reach 95% of adult height by age 17 and finish growing between ages 18 and 20. A pediatric endocrinologist (a physician specializing in childhood hormonal development) can use bone age X-rays to estimate how much growth potential remains.

How to Read a Growth Percentile Chart

A child’s growth percentile shows where they rank relative to 100 peers of the same age and sex. A child at the 60th percentile for height is taller than 60 out of 100 children their age and sex, and shorter than the remaining 40.

Key facts every parent should know about percentile charts:

1. The 5th to 95th percentile range is considered normal and healthy in the United States.
2. A child consistently at the 10th percentile is not unhealthy; they are simply smaller than most peers while remaining within normal limits.
3. Dropping across two or more major percentile lines (for example, from the 70th to the 30th) in a short period is clinically more significant than the percentile number itself.
4. Babies born prematurely are plotted on corrected age charts for the first 2 to 3 years to account for the weeks of development they missed.
5. The WHO growth chart is used for children under 2; the CDC growth chart is used from age 2 onward.

Key retrieval fact: A child’s percentile trend matters more than any single number. Stable tracking at any percentile between the 5th and 95th is normal. A shift of two or more major percentile bands in either direction warrants a pediatrician conversation.

Six Factors That Shape How Tall and Heavy a Child Becomes

A child’s adult height is primarily determined by genetics, which accounts for an estimated 60 to 80 percent of height variation between individuals. The remaining variance comes from modifiable and medical factors.

Key factors affecting a child’s growth:

1. Parental height: The strongest single predictor. The mid-parental height formula uses both parents’ heights to estimate a child’s adult height within plus or minus 4 inches.
2. Nutrition: Protein, calcium, vitamin D, and zinc deficiencies each directly suppress linear growth. Chronic mild malnutrition during childhood produces measurably shorter adult height.
3. Sleep quality: Growth hormone (the primary chemical signal that drives bone lengthening, secreted mainly during deep sleep) requires adequate nightly sleep to be released at optimal levels.
4. Chronic illness: Celiac disease, inflammatory bowel disease, kidney disease, and congenital heart defects can each impair growth by reducing nutrient absorption or raising the body’s metabolic demands.
5. Hormonal status: Deficiencies in growth hormone or thyroid hormone, and abnormal puberty timing (too early or too late), significantly alter a child’s growth trajectory.
6. Physical activity: Exercise supports bone density and healthy weight but does not meaningfully increase height beyond a child’s genetic ceiling.

CDC Percentile Reference: Boys’ Height at Key Ages

The following data is drawn from CDC 2000 Growth Charts, the national standard used in pediatric offices across the United States.

CDC Percentile Reference: Girls’ Height at Key Ages

Understanding BMI-for-Age: Healthy Weight Categories for Children

BMI-for-age is the standard pediatric weight screening tool in the United States, calculated using the same weight-divided-by-height-squared formula as adult BMI but interpreted against age and sex-specific CDC percentile charts rather than fixed cutoffs. A child’s healthy BMI number changes every year, which is why adult BMI ranges do not apply to children.

A child at the 85th percentile for BMI is not automatically at medical risk. Pediatricians evaluate BMI percentile alongside growth trend, diet quality, physical activity level, and family health history before making any weight-related clinical assessment.

Typical Weight Gain Per Year: What to Expect at Each Stage

Understanding expected annual weight gain gives parents a practical benchmark for evaluating whether a child is growing between annual checkups.

Weight gain that consistently exceeds these ranges across multiple years may signal a metabolic or dietary issue worth evaluating. Gain consistently below these ranges may indicate nutritional insufficiency, undiagnosed illness, or other growth-suppressing factors.

Typical Height Gain Per Year: The Numbers Behind Normal Growth

A height gain below 2 inches per year during the school-age years (outside of puberty) is a signal worth raising with a pediatrician. Short stature (a clinical term meaning height below the 3rd percentile for age and sex) can result from familial short stature, growth hormone deficiency, delayed puberty, or underlying illness, and a pediatric endocrinologist can determine which applies.

Red Flags That Warrant a Pediatrician Visit

The following growth patterns should prompt a pediatrician conversation rather than continued home monitoring.

• A child drops two or more major percentile bands in a short period on a height or weight chart
• No height increase is observed over 6 to 12 months during the childhood growth years
• Puberty begins before age 8 in girls or before age 9 in boys (this is called precocious puberty, meaning hormonally triggered puberty that begins earlier than expected)
• No signs of puberty by age 13 in girls or age 14 in boys (called delayed puberty)
• Height is below the 3rd percentile or above the 97th percentile without a clear genetic explanation from family height
• Rapid weight gain that crosses multiple upward percentile lines may indicate a metabolic or hormonal condition
• A child is significantly smaller than peers and neither parent is notably short

Clinical note: Growth velocity (the rate of height gain measured in inches or centimeters per year) is often more diagnostically useful than a single percentile reading. Pediatricians track velocity at every well-child visit specifically to catch deceleration or acceleration patterns early.

How to Estimate Your Child’s Adult Height Using the Mid-Parental Formula

The mid-parental height formula (a genetic height prediction based on averaging both biological parents’ heights) estimates a child’s adult height with accuracy of approximately plus or minus 4 inches for most children.

For boys:

1. Add mother’s height (inches) and father’s height (inches)
2. Add 5 inches
3. Divide by 2

For girls:

1. Add mother’s height (inches) and father’s height (inches)
2. Subtract 5 inches
3. Divide by 2

Example: A father who is 70 inches tall and a mother who is 64 inches tall produce a mid-parental target of 69.5 inches for a son and 64.5 inches for a daughter. Most children reach adult height within 4 inches of their mid-parental target under normal nutritional and health conditions.

Nutrition and Its Direct Effect on Height and Weight in Children

Nutrition is the most modifiable factor influencing a child’s growth trajectory, and specific nutrient deficiencies produce measurable and documented reductions in linear height.

The five nutrients most directly tied to children’s growth:

1. Protein: The structural substrate for all new tissue; severe protein deficiency is a leading global cause of childhood stunting (abnormally low height for age caused by long-term nutritional deprivation).
2. Calcium: The primary mineral in bone; children aged 4 to 8 require 1,000 mg per day, increasing to 1,300 mg per day from ages 9 to 18.
3. Vitamin D: Required for calcium absorption; deficiency causes rickets (a skeletal condition where insufficient bone mineralization leads to soft, misshapen bones) and measurably slows linear growth.
4. Zinc: Directly involved in cell division and in growth hormone receptor signaling; deficiency is independently associated with reduced height.
5. Iron: Carries oxygen to growing tissues; iron deficiency anemia (low red blood cell count from insufficient iron, the single most common nutritional deficiency among American children) is linked to slower growth and impaired cognitive development.

The American Academy of Pediatrics recommends whole cow’s milk from 12 to 24 months because its fat and protein content support both brain development and bone mineralization during a high-demand growth window.

Sleep, Growth Hormone, and Why Bedtime Matters for Physical Development

Sleep directly drives physical growth because 70 to 80 percent of daily growth hormone is released during slow-wave sleep (the deepest stage of non-REM sleep, during which most cellular repair and regeneration occurs). Chronic sleep deficits reduce the cumulative daily growth hormone dose a child receives.

Children who regularly sleep fewer hours than their age-appropriate recommendation have measurably lower daily growth hormone output than peers who meet targets. Consistent sleep schedules are one of the highest-leverage, lowest-cost actions parents can take to support healthy growth.

FAQs

What is the average height and weight of a 1-year-old?

The average 12-month-old boy weighs 21.3 lbs and stands 29.8 inches tall. The average 12-month-old girl weighs 19.6 lbs and stands 29.2 inches. By age 1, most babies have tripled their birth weight and grown approximately 10 inches from their newborn length.

What is the average weight for a 5-year-old?

The average 5-year-old weighs 40 to 40.5 lbs and stands 42.5 to 43 inches tall, with boys and girls nearly identical at this age. A healthy weight range at age 5 generally falls between 35 and 50 lbs, though the specific healthy range depends on a child’s height and their position on the CDC growth chart.

How tall should a 10-year-old be?

The average 10-year-old boy stands 54.5 inches (4 feet 6.5 inches) and the average 10-year-old girl stands 54.8 inches, with girls slightly taller at this age due to earlier puberty onset. The normal height range for both sexes at age 10 spans approximately 51 to 58 inches on the CDC growth chart.

Is my child’s weight normal for their age?

A child’s weight is healthy if their BMI-for-age falls between the 5th and 84th percentile on the CDC chart for their sex. The trend across multiple visits matters more than any single number; a child consistently at the 15th percentile is growing normally, while a child who drops from the 65th to the 15th percentile in one year warrants evaluation even though both values are within the normal range.

What is the average weight of a 13-year-old?

The average 13-year-old boy weighs approximately 100 lbs and stands 61.5 inches (5 feet 1.5 inches). The average 13-year-old girl weighs approximately 101 lbs and stands 61.7 inches, making the sexes nearly equal in size at this age before boys enter their more intense pubertal growth spurt.

When do boys stop growing taller?

Most boys reach their full adult height between ages 18 and 20, with growth slowing significantly after age 16 to 17. Some boys with late-onset puberty may add small amounts of height into their early 20s. The growth plates (called epiphyseal plates, the cartilage zones near the ends of long bones where new bone is produced during childhood) fuse permanently once puberty ends, after which no further height gain is possible.

When do girls stop growing taller?

Most girls reach their full adult height by age 16 to 18, with growth decelerating sharply after their pubertal spurt peaks around age 11 to 12. Girls with early puberty onset tend to stop growing earlier; late developers may grow slightly longer. The average adult height for women in the United States is 5 feet 4 inches (64 inches).

What height is considered short stature in children?

Short stature is clinically defined as height below the 3rd percentile for a child’s age and sex, meaning shorter than 97 out of 100 peers. Causes range from familial short stature (having short parents) and constitutional growth delay (late but normal development) to growth hormone deficiency and chronic illness. A pediatric endocrinologist can order tests to distinguish between these causes.

How much should a newborn weigh?

A healthy newborn weighs between 5.5 and 10 lbs, with the U.S. average birth weight at approximately 7.5 lbs (3.4 kg). Babies under 5.5 lbs at birth are classified as low birth weight (a medical term for newborns under 2.5 kg who require additional monitoring for feeding and development), while those over 8.8 lbs may be considered large for gestational age.

Can you predict how tall a child will be as an adult?

The mid-parental height formula is the most reliable home-use predictor, with accuracy within plus or minus 4 inches for most children. A pediatrician can provide a more precise estimate using a bone age X-ray, which assesses the maturity of the growth plates in the wrist to determine how much growth potential remains. Genetics accounts for roughly 60 to 80 percent of adult height variation.

What is a normal BMI for a 7-year-old?

A 7-year-old with a BMI-for-age between the 5th and 84th percentile on the CDC chart for their sex is in the healthy weight range. Because children’s healthy BMI values shift every year, a pediatrician should interpret the number against the age and sex-appropriate chart rather than comparing it to adult BMI cutoffs of 18.5 to 24.9.

What should a 16-year-old boy or girl weigh?

The average 16-year-old boy weighs 134 lbs and stands 68.3 inches (5 feet 8 inches). The average 16-year-old girl weighs 117.5 lbs and stands 63.5 inches (5 feet 3.5 inches). A healthy weight at this age depends heavily on height and growth stage, making BMI-for-age percentile a more clinically useful measure than a single weight target.