Mid-Parental Height Calculator

About this tool

Predict a child's adult height from the parents

Mid-parental height calculator. Estimates a child's predicted adult height from the parents' heights using the Tanner method, with the standard ±8.5 cm target range, in cm and feet/inches.

RT-HLT-056 · Health & Fitness · Reviewed May 2026

⚠ Disclaimer: For general information only. Not medical advice. RECATOOLS is not a medical device under FDA 21 CFR 820 or EU MDR 2017/745. These calculations are educational and must not replace consultation with a qualified healthcare professional. If you are pregnant, ill, or considering a change to medication or routine, speak with your doctor.

Enter both biological parents' heights and the child's sex to estimate the child's predicted adult height using the Tanner mid-parental method, shown with the standard target range. It's a genetic prediction — a guide, not a guarantee.

Units

Father's height

Mother's height

Child's sex (at birth)

📅 Research current as of 30 May 2026 · Sources: Tanner mid-parental height: boys (father+mother+13)/2, girls (father+mother−13)/2; target range ±8.5 cm.

Rates, regulations, and lender practices change frequently — verify current figures with your provider or licensed advisor before acting.

Predicted adult height

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Enter both parents' heights to begin.

Prediction (cm)

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Prediction (ft/in)

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Range low

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Range high

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How to Use the Mid-Parental Height Calculator

Pick your units

Switch between centimetres and feet/inches with the toggle. The result is always shown in both, so use whichever is easier to enter the parents' heights in.

Enter both parents' heights

Type the biological father's and mother's adult heights as accurately as you can. Small errors in the parents' heights carry straight through to the prediction, so measure rather than guess where possible.

Choose the child's sex

Select boy or girl. The method adds about 13 cm for boys and subtracts about 13 cm for girls — this reflects the average adult height difference between the sexes.

Read the prediction and range

The headline is the mid-parental (target) height. The low–high range shows the spread most children land in. Treat it as a guide, and discuss any growth concerns with your paediatrician.

How Mid-Parental Height Prediction Works

One Simple Formula, Two Versions

The mid-parental height method — often credited to the growth researcher James Tanner — is the most widely used quick estimate of how tall a child will become as an adult. The idea is intuitive: a child's adult height is strongly influenced by the parents, so you average the two parents' heights and then adjust for the child's sex. For a boy, you take the father's height plus the mother's height plus about 13 centimetres, then divide by two. For a girl, you subtract 13 centimetres instead of adding it. That 13-centimetre figure (roughly five inches) is the average difference in adult height between men and women, so adding it for boys and removing it for girls re-centres the parents' average onto the right scale for the child. The result is the "mid-parental height," sometimes called the target height — a single number that represents the genetic midpoint the child is expected to grow towards.

Because no prediction from two numbers can be exact, the method comes with a target range rather than a single promise. The commonly taught range is the mid-parental height plus or minus about 8.5 centimetres, which captures roughly two standard deviations and therefore the great majority of children. A child whose adult height lands anywhere inside that band is growing in line with their genetic potential. This is why paediatricians use the mid-parental height as a reference line on a growth chart: if a child is tracking far above or far below their target range, it can be a prompt to look more closely, whereas tracking within the band is reassuring. The calculation is genetics-only, so it can't see the other influences on final height.

"Mid-parental height is the genetic midpoint a child grows towards — average the parents, shift 13 cm for sex, and allow a ±8.5 cm band. It's a reference line, not a destiny."

What the Number Can and Can't Tell You

A mid-parental height estimate is a useful starting point, but it has real limits and should never be read as a fixed outcome. Final adult height is shaped by far more than the parents' genes: childhood nutrition, general health, chronic illness, hormones, sleep, physical activity, and the timing of puberty all move the dial, and some of these can shift a child well within — or occasionally outside — the predicted range. The formula also assumes the parents reached their own full genetic height, which isn't always true if a parent's own growth was affected by their environment. For families outside the populations the method was first calibrated on, the average sex difference and growth patterns can differ slightly, so the prediction is best treated as a broad guide everywhere rather than a precise figure. The practical takeaway is simple: use the mid-parental height to set expectations and to sense-check a child's growth trajectory, but rely on regular measurements plotted on an appropriate growth chart — and a paediatrician's judgement — for anything that actually matters. If a child is consistently growing outside their target range or crossing percentile lines, that's a conversation to have with a doctor, not something a calculator should settle.

10 Facts About Predicting Adult Height

Boys: (father + mother + 13 cm) ÷ 2 gives the target height.

Girls: (father + mother − 13 cm) ÷ 2.

The 13 cm is the average adult male–female height gap.

The target range is the prediction ± 8.5 cm (≈ ±2 SD).

Most children reach an adult height inside that band.

Paediatricians plot it as a reference line on growth charts.

It's genetics-only — nutrition and health also shape height.

It assumes both parents reached their full genetic height.

Puberty timing can move a child within the range.

It's a guide, not a guarantee — track real measurements.

Frequently Asked Questions

Average the two biological parents' heights and adjust for the child's sex. For a boy: (father's height + mother's height + 13 cm) ÷ 2. For a girl: (father's height + mother's height − 13 cm) ÷ 2. The 13 cm reflects the average adult height difference between men and women. The result is the predicted adult "target" height, and most children land within about ±8.5 cm of it.
It's a reasonable estimate but not exact. The method explains the genetic midpoint, and the ±8.5 cm range captures most children, but final height also depends on nutrition, health, hormones, sleep, and puberty timing. Roughly speaking the prediction is good to within a few centimetres for most kids, while a minority finish noticeably taller or shorter than the midpoint. Use it as a guide and rely on growth-chart tracking for anything important.
Because, on average, adult men are about 13 cm (around 5 inches) taller than adult women. To predict a boy's height you shift the parents' average up by that amount; to predict a girl's you shift it down. This re-centres the mid-point onto the correct scale for the child's sex. Some references use a slightly different constant, but 13 cm is the standard value taught in paediatrics.
The target (or genetic) height range is the mid-parental height plus or minus about 8.5 cm, which corresponds to roughly two standard deviations. The great majority of children reach an adult height somewhere inside this band. Paediatricians draw it on a growth chart as a reference: a child tracking within the band is growing in line with their genetic potential, while one tracking well outside it may warrant a closer look.
Yes. The range covers most children but not all. Factors the formula can't see — nutrition, chronic illness, hormone levels, early or late puberty, and the fact that a parent may not have reached their own full genetic height — can push a child above or below the band. Growing outside the predicted range isn't automatically a problem, but if a child is consistently outside it or crossing percentile lines on a growth chart, it's worth discussing with a doctor.
The mid-parental method needs both biological parents' heights, because it averages them. If you only know one, the prediction won't be reliable — you'd be guessing at half the input. If a parent's height is genuinely unknown, you could substitute the average adult height for their sex in your country as a rough stand-in, but understand that this widens the uncertainty considerably. For the most meaningful estimate, use both real heights.
The mid-parental height prediction is based only on the parents, so it gives the same target from birth onwards — you don't need the child's current height or age to use it. It's most useful as a reference line to compare against the child's actual growth as they get older. Other prediction methods that use a child's current height, age, and bone age can refine the estimate during childhood, but those require clinical measurements.
Genetics is the dominant factor — studies suggest roughly 80% of the variation in adult height within a well-nourished population is heritable, which is why the parents' heights predict so much. The remaining portion comes from environment, especially nutrition and health during the growing years. In populations where childhood nutrition is poor, the environmental share is larger. The mid-parental method captures the genetic part; good nutrition and health help a child reach the top of their genetic potential rather than fall short of it.
No. Everything is calculated in your browser. The heights you type are never sent to a server, stored, or shared — the prediction runs entirely on your device. You can use it freely without creating an account or entering any personal details, and nothing about the child or the parents is recorded by RECATOOLS.
Not on its own. A single snapshot below the mid-parental height is common and often just reflects timing — for example, a late developer catches up after puberty. What matters more is the trend: a child who grows steadily along their own percentile is usually fine, even if that percentile is below the parental prediction. Concerns arise when a child crosses percentile lines downwards, grows very slowly, or sits far outside the target range. If you're worried, your paediatrician can assess growth velocity and, if needed, check bone age — that's the right place for this, not a calculator.

Mid-Parental Height Calculator