Mid Parental Height Calculator

Q: What is the mid-parental height formula in inches?

Add both parents' heights in inches, divide by 2, then: Boys: add 2.5 inches Girls: subtract 2.5 inches The likely range is about 3.3 inches above and below that number. Example: dad 70 in, mom 64 in. Average is 67 in. A boy's target is 69.5 in. A girl's target is 64.5 in.

Q: What is the difference between familial short stature and constitutional growth delay?

Familial short stature means the child is short because the parents are short. Growth is steady, puberty is on time, and the child ends up near the family target. Constitutional growth delay means the child is a late bloomer. They grow slowly and start puberty late, but keep growing longer than friends and often reach a normal adult height.

Data Complete?	—
Evaluation Appropriate?	—
Raw Mid-Parental Height	—
Target Height (Gender-Adjusted)	—
Predicted Height Range	—
Z-Score	—
Height Percentile	—

Data Complete?

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Evaluation Appropriate?

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Raw Mid-Parental Height

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Target Height (Gender-Adjusted)

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Predicted Height Range

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Z-Score

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Height Percentile

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Introduction

The Mid Parental Height Calculator estimates how tall a child may be as an adult. It rests on one simple idea: kids tend to grow to a height close to the average of their two biological parents. Doctors call this the mid-parental height, or target height.

To use it, enter the father's height, the mother's height, and the child's sex. The tool averages the two parent heights, then adds 6.5 cm for a boy or subtracts 6.5 cm for a girl. You can type heights in centimeters, inches, feet and inches, meters, or millimeters, and show results in any of those units.

The calculator returns a target height plus a likely range of about 8.5 cm above and below it. Most children land somewhere inside that range. You also get a z-score and a height percentile based on CDC growth data, a visual scale, a bar chart, and a step-by-step look at the math.

This is an estimate, not a promise. Genes, food, sleep, puberty timing, and health all change how a child grows. If a child's growth seems far off from this range, or growth slows down, talk to a pediatrician.

How to use our Mid Parental Height Calculator

Enter the child's sex and both biological parents' heights. The calculator shows the child's target adult height, a likely height range, a z-score, and a percentile.

Purpose Check: Pick "Yes" if you want to estimate a child's adult height from the parents' heights. If you pick "No", the calculator turns off, since this tool is not built for other uses.

Child's Sex: Choose Male or Female. Boys get +6.5 cm added and girls get 6.5 cm taken away from the parents' average height.

Father's Height: Type the father's height. Use his real adult height, measured without shoes.

Unit for Father's Height: Pick cm, in, ft + in, mm, or m. If you pick ft + in, you fill in two boxes: feet and inches.

Mother's Height: Type the mother's height, also measured without shoes.

Unit for Mother's Height: Pick the unit that fits your number. It can be different from the father's unit.

Display results in: Choose the unit for your answers: cm, in, ft + in, mm, or m. This does not change your input units.

Decimal places: Choose 0, 1, 2, or 3 decimal places for the results.

Calculate: Click this button to see the mid-parental height, the predicted height range, the chart, and the step-by-step math.

Reset: Click this to clear your entries and start over with the default values.

What Is Mid-Parental Height?

Mid-parental height is a simple way to guess how tall a child will be as an adult. It uses the heights of the child's two biological parents. Height is mostly passed down from parents, so their heights give a good clue about a child's future height. Doctors also call this the target height or genetic potential height.

The Mid-Parental Height Formula

First, add both parents' heights and divide by 2. That gives the raw mid-parental height. Then adjust it for the child's sex:

Boys: (father's height + mother's height) ÷ 2, then add 6.5 cm (about 2.5 inches)
Girls: (father's height + mother's height) ÷ 2, then subtract 6.5 cm (about 2.5 inches)

The 6.5 cm is added or taken away because adult men are, on average, about 13 cm (5 inches) taller than adult women.

Why There Is a Range

No formula can name one exact number. Most children end up within about 8.5 cm (3.3 inches) above or below their target height. That band covers roughly the 3rd to 97th percentile, so about 95 out of 100 children land inside it. Always read the result as a range, not a promise.

Why Doctors Use It

Pediatricians compare a child's growth chart to the mid-parental height. If a child is growing along a curve that matches the family target, growth is likely normal, even if the child is short or tall for their age. If the child's growth falls far below or above the target range, the doctor may look for a cause, such as a hormone problem, poor nutrition, a bone condition, or a delay in puberty.

What Can Change the Result

Mid-parental height is only an estimate. Other things also shape final adult height:

Nutrition and overall health during childhood
Long-term illness or some medicines
Timing of puberty (early or late)
Birth weight and growth in the first two years
Sleep, exercise, and hormone levels

Use measured heights, not guessed ones, for the best result. Ask both parents to be measured without shoes. If a child's growth worries you, talk to a pediatrician. This estimate does not replace medical advice or a full growth check.

Formulas used

Raw Mid-Parental Height

\text{Raw MPH} = \frac{\text{Father's Height} + \text{Mother's Height}}{2}

Target (Gender-Adjusted) Height

\text{Target Height} = \text{Raw MPH} \pm 6.5\ \text{cm} \quad (+\ \text{male},\ -\ \text{female})

Predicted Adult Height Range (3rd-97th percentile)

\text{Range} = \text{Target Height} \pm 8.5\ \text{cm}

Z-Score from CDC LMS Reference (240 months)

Z = \frac{\left(\frac{X}{M}\right)^{L} - 1}{L \times S}

Height Percentile from Z-Score

P = \Phi(Z) \times 100\%

Height Unit Conversion to Centimetres

\text{cm} = (\text{ft} \times 30.48) + (\text{in} \times 2.54), \quad \text{cm} = \text{mm} \times 0.1, \quad \text{cm} = \text{m} \times 100

Centimetres to Feet and Inches

\text{ft} = \left\lfloor \frac{\text{cm}}{2.54 \times 12} \right\rfloor, \quad \text{in} = \frac{\text{cm}}{2.54} - 12 \times \text{ft}

Frequently asked questions

Can a child grow taller than both parents?

Yes. Height comes from many genes, and kids can get a taller mix than either parent. Better food, sleep, and health can also add height over the family average.

About 1 in 20 children end up outside the predicted range, above or below it. A child who passes both parents is usually still healthy and normal.

Does a child get height from the mother or the father?

Both. Height is set by hundreds of genes, and each parent passes down about half. That is why the formula averages the two parents instead of using just one.

No single gene comes from only the mother or only the father. A tall dad does not matter more than a tall mom.

How much of a person's height comes from genes?

About 80% of height is set by genes. The other 20% comes from things like food, sleep, exercise, and illness during childhood.

That is why kids in the same family usually end up close in height, but not exactly the same.

What is the mid-parental height formula in inches?

Add both parents' heights in inches, divide by 2, then:

Boys: add 2.5 inches
Girls: subtract 2.5 inches

The likely range is about 3.3 inches above and below that number.

Example: dad 70 in, mom 64 in. Average is 67 in. A boy's target is 69.5 in. A girl's target is 64.5 in.

At what age do kids stop growing?

Most girls stop growing around age 14 to 16, about 2 years after their first period. Most boys stop around age 16 to 18, though some grow a little into their late teens.

Growth stops when the growth plates in the bones close. A doctor can check this with a hand X-ray called a bone age test.

How close is mid-parental height to a child's real adult height?

It is a good guess, not an exact answer. About 95 out of 100 kids land within 3.3 inches (8.5 cm) of the target.

It works best when both parents had normal childhood growth. It works less well if a parent was short from illness or poor food, since that short height was not caused by genes.

What does it mean if a child is much shorter than their target height?

It can be a sign worth checking. Doctors look at growth over time, not one measurement. A child growing steadily on their own curve is usually fine.

If a child drops across percentile lines or is far below the family target, a doctor may test for thyroid problems, growth hormone issues, celiac disease, or other causes.

What is the difference between familial short stature and constitutional growth delay?

Familial short stature means the child is short because the parents are short. Growth is steady, puberty is on time, and the child ends up near the family target.

Constitutional growth delay means the child is a late bloomer. They grow slowly and start puberty late, but keep growing longer than friends and often reach a normal adult height.

How do you measure height correctly at home?

Take off shoes and any hair bands or bulky hair styles. Stand with heels, bottom, and shoulders against a flat wall, feet together, looking straight ahead.

Place a flat book on the head, level with the floor, and mark the wall. Measure from the floor to the mark with a tape measure. Measure twice and use the average.

What if one parent's height is not known?

You can use the average adult height for that parent's sex as a stand-in: about 5 ft 9 in (175 cm) for men and 5 ft 4 in (162 cm) for women in the U.S.

The answer will be less exact. Treat it as a rough guide only, and lean on the child's own growth chart instead.

Is it true that a child's adult height is double their height at age 2?

It is a rough rule, not a reliable one. Doubling the height at age 2 works better for boys. For girls, doubling the height at about 18 months is closer.

This trick can be off by several inches. The parent-average method is usually a better guess.

How much do kids grow during puberty?

Boys gain about 10 to 12 inches (25 to 30 cm) during the puberty growth spurt. Girls gain about 8 to 10 inches (20 to 25 cm).

Girls start their spurt around age 10 to 12, boys around 12 to 14. Growth slows fast after the spurt ends.

Can better food or more sleep make a child taller?

It can help a child reach their full genetic potential, but it will not push them far past it. Protein, calcium, vitamin D, and iron matter most.

Growth hormone is released mostly during deep sleep, so kids need 9 to 12 hours a night depending on age. No food or supplement adds inches beyond what genes allow.

What is the Khamis-Roche method for predicting height?

It is another way to predict adult height. It uses the child's current age, height, and weight along with both parents' heights.

It is often a bit more exact than the parent-average method for kids aged 4 to 17, because it uses the child's own growth so far. It does not need an X-ray.

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