Quick Answer

A height calculator converts measurements between centimeters, meters, feet and inches. A child height predictor estimates possible adult height using parents' heights and, in some methods, the child's current age, height and weight. The most common simple prediction is the mid-parental height formula. For a boy, add the mother's height, father's height and 13 cm, then divide by 2. For a girl, add the mother's height and father's height, subtract 13 cm, then divide by 2. The result is only an estimate because growth also depends on nutrition, health, sleep, hormones, puberty timing and measurement accuracy.

For quick tool navigation, RevisionTown also has a Height Calculator, a dedicated Pediatric Height Predictor Calculator, a Height Converter, and a Height Percentile Calculator. This article explains the formulas behind those tools and how to interpret the numbers without overclaiming accuracy.

The most important rule is to separate three different questions. First, "How tall is this person now?" is a measurement question. Second, "What does this height equal in another unit?" is a conversion question. Third, "How tall might this child become?" is a prediction question. Mixing those questions causes confusion. A precise conversion can be exact, but an adult-height prediction is never exact.

Height Conversion Formulas

Height conversions are based on fixed unit relationships. These are exact mathematical conversions, unlike child-height prediction. The key values are:

To convert feet and inches to centimeters, convert feet to inches, add the extra inches, then multiply by 2.54:

For example, a height of 5 ft 10 in is:

To convert centimeters to feet and inches, divide by 2.54 to get total inches. Then divide total inches by 12. The whole number is feet, and the remainder is inches:

If a height is 175 cm, then total inches are \(175\div2.54=68.90\). That is 5 full feet, with \(68.90-60=8.90\) inches remaining. So 175 cm is about 5 ft 8.9 in, often rounded to 5 ft 9 in for everyday use.

For fast unit tools, use RevisionTown's Meters and Centimeters Calculator, Feet and Inches Calculator, or broader Length Conversion Calculator. Natural internal linking matters here because users who need height conversion often need adjacent length conversions, not only health interpretation.

Rounding should match the purpose. For a clothing size estimate, rounding to the nearest inch may be fine. For a child's growth record, use a more precise measurement and record the same unit consistently. A difference of 0.5 cm may not matter for casual conversion, but it can matter when tracking a young child's growth pattern over time.

How to Measure Height Accurately

A calculator is only as good as the input. Many height errors come from measurement, not from the formula. The CDC advises measuring children barefoot, without bulky clothing or hair accessories that interfere with the measurement, standing on firm flooring against a flat surface, with feet flat and together, legs straight, arms at the sides and shoulders level. The child should look straight ahead rather than tilting the chin up or down.

For home measurements, a wall and a flat headpiece can work if done carefully, but a stadiometer is more reliable. Measure at roughly the same time of day when comparing records. Human height can vary slightly during the day because spinal discs compress under normal activity. This is why repeated measurements taken under different conditions can create small apparent changes that are not true growth.

In a child-height predictor, a 1 cm error in a parent's height, or a 1 cm error in the child's current height, may not sound dramatic, but it can affect the final result. More importantly, poor measurement can create false worry. A child may seem to have slowed growth when the previous measurement was too high or the new measurement is too low. This is why pediatric offices use standardized procedures.

Child Height Predictor: How Adult Height Is Estimated

A child height predictor estimates possible adult height. It does not know the future. It uses patterns from genetics and growth data to create a reasonable range. Parents' heights are important because genetics is a major influence on adult height, but genetics is not the only factor. Nutrition, chronic illness, endocrine conditions, sleep, physical activity, emotional stress and puberty timing can all affect growth.

The simplest common method is mid-parental height. Use the same unit for both parents. In centimeters, the formulas are:

In inches, the same idea is usually expressed with 5 inches instead of 13 cm:

For example, if the mother is 165 cm and the father is 180 cm, the estimated adult height for a boy is:

For a girl with the same parents, the estimate is:

The estimate should be treated as a target range, not a fixed point. A child may end up above or below the mid-parental estimate and still be healthy. Mayo Clinic notes that most children reach an adult height within about 2 inches of mid-parental height, but individual variation is real. Other clinical references often describe a wider expected range around target height. This is why a single number should not be used to label a child's growth as normal or abnormal.

Some predictors also use the child's current age, height and weight. These models may be more informative for older children because current height already reflects part of the child's growth pattern. However, they can still be affected by ethnicity, population data, puberty timing, measurement error and health status. A predictor built from one population may not fit every child equally well.

Child Height Prediction Methods by Age

Not every child height predictor is useful at every age. A newborn's length is influenced by pregnancy, birth timing, measurement difficulty and prenatal conditions, so it is not a precise adult-height forecast. A teenager who has nearly completed puberty has a much more visible growth pattern. Between those extremes, prediction becomes a mixture of family height, current growth curve, puberty timing and health context.

The table below explains common approaches. It is not a ranking from best to worst. Each method answers a slightly different question. A parent who wants a quick family-based estimate may use mid-parental height. A clinician evaluating growth concern may use serial growth measurements, growth velocity, pubertal stage, bone age and medical history. An online calculator cannot replace that full assessment.

Infants and toddlers

For infants and toddlers, growth monitoring is usually more important than adult-height prediction. Length measurements in babies can be harder to take accurately because the child must be positioned correctly while lying down. Small measurement errors can look large on a chart. At this stage, clinicians often focus on whether the child is growing consistently, feeding well and meeting broader developmental expectations.

The common "double the height at age two" idea is easy to remember, but it is not precise enough to rely on for health decisions. It may produce a ballpark estimate for some children, but it ignores parental height, puberty timing and individual growth pattern. If a parent wants a simple number for curiosity, it can be harmless. If a parent is worried about unusually slow or fast growth, a growth chart and clinician review are more useful.

School-age children

For school-age children, repeated height records become more informative. A child who grows steadily near the same percentile is often following their own pattern. A child whose height percentile changes sharply may need a closer look. This does not mean every percentile change is a problem, but it does mean the trend deserves context. Illness, nutrition changes, puberty timing, medication and measurement differences can all affect the apparent pattern.

At this age, mid-parental height can be compared with the child's growth curve. If a child is far outside the expected family range, that is a reason to ask better questions. It is still not a diagnosis. Some families have broad height variation, and some children have constitutional growth delay, meaning they grow later and may reach adult height later than classmates.

Puberty and teenage years

During puberty, height prediction becomes complicated because timing matters. Two children of the same age and same current height may have very different remaining growth if one has already passed the main growth spurt and the other has not started it. Puberty can create temporary differences that later narrow. Early-maturing children may be tall for age in middle school but stop growing sooner. Later-maturing children may look short temporarily and continue growing later.

For teenagers, adult-height prediction should be interpreted with puberty stage. A simple mid-parental formula still gives family context, but it cannot estimate remaining growth as well as a clinical assessment that considers skeletal maturity. If final height is a major concern, especially with delayed puberty or very rapid puberty, a pediatric clinician can decide whether further evaluation is needed.

How to choose the right calculator

Use the main height calculator when you need basic unit conversion or a general overview. Use the pediatric height predictor when the question is "How tall might my child become?" Use a percentile calculator when the question is "Where does this measurement sit compared with children of the same age and sex?" Use BMI tools only when the question involves height and weight together. For a broad directory of related tools, the Health and Fitness Calculators page can help users move from height to adjacent calculators without mixing unrelated methods.

Growth Charts and Percentiles

Growth charts show how a child's measurement compares with a reference population of children of the same age and sex. A height percentile is not a grade and not a health score. If a child is at the 25th percentile for height, that means the child is taller than about 25 percent of children in the reference group and shorter than about 75 percent. Many healthy children grow at lower or higher percentiles.

The CDC explains that growth charts are tools that contribute to an overall clinical impression and are not meant to be used as the only diagnostic instrument. The WHO Child Growth Standards are commonly used for younger children and describe growth under conditions believed to support healthy development. CDC clinical growth charts are widely used for children and adolescents in the United States.

The most useful part of a growth chart is the pattern. A child who has followed the 15th percentile steadily may be growing normally for that child. A child who drops from the 75th percentile to the 25th percentile over time may need attention, even if the new percentile is still within a broad range. The direction and speed of change matter.

Growth charts are especially helpful when combined with age, puberty status, medical history and family pattern. If a child is short but both parents are short and the child grows steadily, the interpretation is different from a child who was previously average height and then slows sharply. Online calculators cannot evaluate the full medical picture.

How to Track Growth Records at Home

Home tracking can be helpful when it is calm, consistent and not excessive. The goal is not to measure a child every few days. Height changes slowly, and frequent measurement can create anxiety without adding useful information. A better approach is to record height at reasonable intervals, use the same method each time, and bring the record to routine pediatric visits if there are concerns.

A useful home growth record should include the date, age, measured height, unit, measuring method and any note that might affect interpretation. For example, record whether the measurement was taken with shoes off, whether the child was standing against a flat wall, and whether the same measuring tape or stadiometer was used. If one measurement is surprisingly different from the previous trend, remeasure before assuming a true change.

When calculating growth velocity, use measurements separated by enough time to be meaningful. A simple annualized growth velocity can be estimated as:

If a child grows from 130 cm to 136 cm over 12 months, the growth velocity is 6 cm per year. If the same change happens over 18 months, the annualized velocity is:

This number still needs context. Growth velocity varies by age and puberty stage. A toddler, a prepubertal child and a teenager in a growth spurt should not be judged by the same expectation. Use velocity as a discussion aid, not a standalone diagnosis.

How often should you measure?

For most children, routine pediatric measurements are enough. If you are tracking at home, spacing measurements several months apart is usually more useful than weekly measurement. The shorter the interval, the more measurement noise matters. A child may seem unchanged over a few weeks simply because height does not increase smoothly day by day, or because one measurement was off by a few millimeters.

If a clinician has asked you to monitor growth more closely, follow that professional's instructions. Some medical situations require structured tracking. For general curiosity, however, keep measurement relaxed and infrequent. A child's height should not become a source of pressure or comparison.

How to talk about height with children

Height is sensitive because children compare themselves with classmates, siblings and sport teams. A calculator should not become a tool for criticism. Avoid telling a child they are "too short," "too tall," "behind," or "not growing enough" based only on an online result. A healthier approach is to say that people grow at different times, families have different height patterns, and doctors look at steady growth over time.

If the child is old enough to understand, explain that a percentile is not a score. It is just a comparison with a reference group. A child at the 10th percentile is not failing, and a child at the 90th percentile is not automatically healthier. What matters is whether the child is growing well for their own body and health history.

BMI from Height and Weight

BMI, or body mass index, uses height and weight to create a screening number. For adults, BMI is often grouped into categories, but it does not directly measure body fat or health. For children and teens, BMI must be interpreted by age and sex percentiles, not by adult cutoffs alone. This is one reason child growth tools should be used carefully.

The metric BMI formula is:

If someone weighs 70 kg and is 175 cm tall, first convert height to meters:

The imperial BMI formula is:

RevisionTown has a Body Mass Index BMI Calculator and a shorter BMI Calculator for quick calculation. Use BMI as a screening tool, not a final judgement. Athletes, pregnant people, older adults, children, teens and people with different body compositions may need more context than BMI provides.

Ideal Weight for Height: Useful but Limited

Many users search for ideal weight by height, but "ideal weight" is not a single universal number. Healthy weight can vary with age, sex, body composition, muscle mass, frame size, ethnicity, activity level and medical history. Online formulas can be useful for broad comparison, but they should not be treated as a personal medical target.

One widely known adult formula is the Devine formula, historically used for medication dosing references rather than modern personal fitness goals. It estimates weight from height above 5 feet. In inches:

For a 70-inch adult, the formula gives:

This does not mean 73 kg is the only healthy weight for a 70-inch adult. It is a formula result, not a full health assessment. If you need a quick tool, see RevisionTown's Ideal Weight Calculator. If body composition is the real question, a Body Fat Percentage Calculator may be more relevant than height alone.

Adult Height Changes, Posture and Measurement Differences

Many adults assume their height is fixed forever, but measured height can change slightly for several reasons. The most common short-term reason is daily spinal compression. A person may measure a little taller in the morning and a little shorter later in the day after standing, walking and sitting. This is normal and usually small, but it can explain why a driver's license height, clinic height and home height do not always match exactly.

Posture also affects adult measurement. Rounded shoulders, forward head position, scoliosis, kyphosis, pain, injury or difficulty standing fully upright can reduce measured standing height. In older adults, gradual height loss can occur with age because of changes in spinal discs, posture and bone health. A noticeable or rapid loss of height should be discussed with a healthcare professional because it can sometimes relate to vertebral compression fractures, osteoporosis or other conditions.

For adults using height in a BMI calculator, small measurement differences usually do not change the interpretation dramatically, but they can shift a value near a category boundary. If accuracy matters, measure barefoot with a reliable method, record the measurement in centimeters or inches, and use that same value consistently. If your goal is clothing, sports, military standards or medical tracking, use the measurement standard required by that context.

Adults sometimes use height calculators to compare historical heights, such as a school sports record, a passport entry or a recent clinic measurement. When those numbers differ by less than an inch, measurement conditions may explain the difference. When the difference is larger, especially with back pain, posture change or older age, it is worth checking with a clinician rather than assuming the calculator is wrong.

Army Height and Weight Context

Some users search for height calculators because they need height and weight information for military standards. These standards are not the same as general health advice. Military requirements depend on the specific branch, country, age, sex and current policy. They can also involve body-composition assessment if weight tables are exceeded.

RevisionTown has an Army Height and Weight Calculator for users who need a dedicated tool. Use it separately from child-height prediction. A child height predictor estimates possible adult stature; a military height-weight tool checks rules for a specific administrative standard.

When using any standard table, check the current official policy. Do not rely only on a blog article or old chart for eligibility decisions. Standards can change and may include waivers, body-composition measurements or medical review.

Worked Examples

Example 1: Convert 5 ft 6 in to centimeters

First convert the height to total inches:

So 5 ft 6 in is 167.64 cm, often rounded to 168 cm for everyday use.

Example 2: Convert 182 cm to feet and inches

So 182 cm is about 5 ft 11.7 in, often rounded to 6 ft 0 in depending on the context.

Example 3: Estimate adult height for a boy

Suppose the mother is 160 cm and the father is 178 cm.

The mid-parental estimate is 175.5 cm. This should be interpreted as an approximate family-based estimate, not a promise.

Example 4: Estimate adult height for a girl

Using the same parents:

The mid-parental estimate is 162.5 cm. Growth chart tracking and health context matter more than the formula alone.

Example 5: Calculate BMI from kg and cm

For an adult who is 80 kg and 180 cm:

This is a screening number. It should be interpreted with body composition, age, medical history and clinical context.

Common Mistakes When Using a Height Calculator

When to Ask a Pediatrician About Growth

Most variation in height is normal. Some children are naturally short, some are naturally tall, and puberty timing can create large differences between children of the same age. However, growth concerns deserve professional review when the pattern is unusual or changing. A calculator cannot evaluate medical history, birth history, nutrition, puberty stage, medications or family conditions.

Consider asking a pediatric clinician if a child is crossing downward across multiple percentile lines, has very slow growth over time, is much shorter than expected from family height, has delayed or very early puberty, has chronic digestive symptoms, has poor appetite or weight loss, has persistent fatigue, or has a known condition that may affect growth. The clinician may review growth records, family heights, nutrition, puberty stage and, when appropriate, laboratory tests or bone-age imaging.

It is also worth asking when measurements seem inconsistent. Sometimes the issue is not growth but measurement method. A clinic can remeasure height accurately and compare the result with previous records. This is especially important if online calculations are causing worry.

Height Calculator FAQs

What is the best height calculator?

The best height calculator depends on the question. Use a height converter for unit conversion, a pediatric height predictor for adult-height estimates, a percentile calculator for growth-chart context, and a BMI calculator for height-weight screening.

How accurate is the mid-parental height formula?

It is a rough family-based estimate. Many children finish near the estimate, but some do not. The formula does not fully account for puberty timing, health, nutrition, chronic conditions, ethnicity, environment or measurement error.

Can a short child become a tall adult?

Yes, depending on genetics, puberty timing and health. Some children with later puberty grow for longer. A pediatrician can interpret whether a child's growth pattern fits normal variation.

Can tall parents have a shorter child?

Yes. Children inherit a mix of genetic factors, and final height varies around the family estimate. Health and puberty timing also affect adult height.

What is the formula for height in cm from feet and inches?

Use \((12\times\text{feet}+\text{inches})\times2.54\). For example, 6 ft 1 in is \((72+1)\times2.54=185.42\) cm.

What is the formula for BMI using cm and kg?

Convert centimeters to meters by dividing by 100, then use \(\text{BMI}=\frac{\text{kg}}{\text{m}^2}\).

Should I worry if my child is below the 10th percentile?

Not automatically. Some healthy children are naturally smaller. The trend over time, family height, growth velocity, puberty stage and clinical context are more important than one percentile value.

Which growth charts should I use?

Use the chart recommended by your local clinician or health system. WHO standards are widely used for younger children, and CDC growth charts are widely used for children and adolescents in the United States.

Is height affected by nutrition?

Yes. Severe or chronic nutritional problems can affect growth. However, in well-nourished children, genetics and puberty timing often explain much of normal height variation.

Can exercise make a child taller?

Regular activity supports general health, but it cannot override genetics. Sleep, nutrition and health matter, but no exercise program can guarantee extra adult height.

Final Takeaway

A height calculator is useful when it is used for the right job. Unit conversions can be exact. BMI can provide a quick screening number. Mid-parental height can estimate a child's likely adult-height range. Growth charts can show whether a child is following a steady pattern. But none of these tools should be treated as a diagnosis or a perfect prediction.

For everyday use, measure carefully, keep units consistent, interpret predictions as ranges, and focus on growth trends rather than one result. For health concerns, especially in children, use the calculator as a starting point for a better conversation with a pediatric professional.