Mid-Parental Height Calculator

CHILD GROWTH HEALTH HEIGHT PREDICTION PARENTING
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By Checked against sources by , Founder & Architect, RECATOOLS Published Updated Last reviewed

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.

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Mid-Parental Height Calculator

⚠ 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.

Father's height
cm
Mother's height
cm
📅 Research current as of 14 Oct 2026 · Sources: Tanner et al. 1970 mid-parental height: boys (father+mother+13)/2, girls (father+mother−13)/2; target range ±8.5 cm, as reviewed by Ciancia et al., BMC Pediatrics 2025, and Zeevi et al., Children 2024.
Reference ranges and clinical guidance are revised over time — confirm against current local protocol and a qualified clinician’s judgement before acting on these figures.
Target (mid-parental) 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 is Tanner's ±8.5 cm target range around it. Treat it as a guide, and discuss any growth concerns with your paediatrician.

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How Mid-Parental Height Prediction Works

One Simple Formula, Two Versions

The mid-parental height method, published by Tanner and colleagues in 1970, 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 estimate from two numbers can be exact, the method comes with a target range rather than a single promise. Tanner's range is the mid-parental height plus or minus 8.5 centimetres, which a 2025 review in BMC Pediatrics describes as reflecting the variation within a family. A 2024 study in the journal Children describes it as Tanner's 3rd-to-97th-centile band and notes that Tanner later widened it to ±9 cm for girls and ±10 cm for boys; the American Academy of Pediatrics' teaching material uses ±10.2 cm. How many children actually finish inside ±8.5 cm depends on the families: in Francis Galton's published records of 934 adult children from 205 Victorian English families, about one in eight finished outside it (our count from that dataset). Paediatricians draw the mid-parental height as a reference line on a growth chart. The calculation is genetics-only, so it can't see the other influences on final height.

Very Tall and Very Short Parents

The formula centres every family's band on the parents' own average. Children of unusually tall or unusually short parents tend to finish closer to the population average than that — the regression to the mean Galton described in the 1880s. In a study of 419 children aged 8–9, Wright and Cheetham (Archives of Disease in Childhood, 1999) found that 90% were within 1.5 SDS of their reported mid-parental height, but "where parents were unusually tall or short, their children were relatively less tall or short". Luo, Albertsson-Wikland and Karlberg (Pediatric Research, 1998), in a Swedish population study, reported that the Tanner method may underestimate target height by up to 6 cm when mid-parental height is very low. In Galton's families the same pattern shows: children of the shortest couples finished on average about 3 cm above the target, and children of the tallest couples about 2 cm below it (our arithmetic). Corrected methods exist, such as Hermanussen and Cole's (2003) and Luo's population equation, but each depends on a reference population, so this calculator shows Tanner's uncorrected formula. For very tall parents the estimate tends to run high, and for very short parents low.

"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.

The 13 cm is the average gap between adult men and women

01

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

02

Girls: (father + mother − 13 cm) ÷ 2.

03

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

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The target range is ± 8.5 cm, Tanner's 1970 band; the AAP's teaching material uses ± 10.2 cm.

05

In Galton's Victorian families, about 7 in 8 adult children finished inside ± 8.5 cm.

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Paediatricians plot it as a reference line on growth charts.

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

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It assumes both parents reached their full genetic height.

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Puberty timing can move a child within the range.

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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 "target" height, and Tanner's target range is ±8.5 cm around it.
  • It's an estimate, not an exact figure. In Francis Galton's published records of Victorian English families, just under two-thirds of adult children finished within 5 cm of this target and about seven in eight within ±8.5 cm (our count from that dataset); modern families may differ. Children of very tall or very short parents tended to finish closer to the average than the formula suggests. Final height also depends on nutrition, health, hormones, sleep and puberty timing. 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. The real gap varies by population: a 2025 review in BMC Pediatrics cites 14.4 cm for a Flemish population, 13.9 cm for an Italian one and 15.8 cm for an Indian one, and in 1990 Japanese researchers proposed adding 2 cm for the rise in height between generations, a correction the same authors later revisited. 13 cm remains the value Tanner used and the one most widely taught; the same review notes that the 1990 UK growth charts show a 13.2 cm gap.
  • The target height range is the mid-parental height plus or minus 8.5 cm, Tanner's 1970 figure for the spread of heights within a family, described in a 2024 study in Children as the 3rd-to-97th-centile band. It is not the only width in use: the same study reports that Tanner later widened it to ±9 cm for girls and ±10 cm for boys, and the American Academy of Pediatrics' teaching material uses ±10.2 cm. How many children finish outside it depends on the families measured; in Galton's Victorian English records it was about one in eight (our count). Paediatricians draw it on a growth chart as a reference line.
  • Yes. Children of unusually tall or short parents tend to finish closer to the population average than the parents' own average — regression to the mean — and Tanner's formula does not allow for that. Wright and Cheetham (Archives of Disease in Childhood, 1999), studying children aged 8–9, found that "where parents were unusually tall or short, their children were relatively less tall or short". Luo and colleagues (Pediatric Research, 1998) reported that the Tanner method may underestimate target height by up to 6 cm when mid-parental height is very low. So for very tall parents the estimate tends to run high, and for very short parents low. Corrected methods (Hermanussen and Cole, 2003; Luo's equation) depend on a reference population, so this calculator shows Tanner's original formula.
  • 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.
  • Height is strongly heritable. In a Swedish population study, Luo, Albertsson-Wikland and Karlberg (Pediatric Research, 1998) estimated its heritability at 0.75–0.78. A heritability figure describes how much of the variation in height across a population goes with genetic differences; it does not say what share of one child's height came from the parents, and it differs between populations and studies. Brothers and sisters still differ because each inherits a different mix of the parents' genes, and the rest of the variation goes with environment, such as nutrition and health during the growing years. The mid-parental method uses only the parents' heights.
  • 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.
  • This calculator can't answer that. It knows only the parents' heights, not the child's measurements, age or health. Paediatricians judge growth from repeated measurements plotted on a growth chart, with the mid-parental height as one reference line among several. If you have a concern about a child's growth, that's a question for your paediatrician, not a calculator.

Method & sources

How it computes

Tanner et al. 1970 target height: boys (father + mother + 13 cm) / 2, girls (father + mother - 13 cm) / 2; target range +/- 8.5 cm, uncorrected for regression to the mean. Parent heights 120-230 cm accepted. Shown in cm and ft/in (total inches rounded before splitting). GrowthKernel.midParentalHeight and formatFtIn, tested.

What this tool implements

  • Formula and range checked against Ciancia, Ribes Cajas and Cools (BMC Pediatrics 2025) and Zeevi et al. (Children 2024): the +/-8.5 cm range is Tanner's 1970 band, read as the 3rd-97th centile and said to reflect within-family variance; Tanner later widened it to +/-9 cm (girls) and +/-10 cm (boys), and the AAP teaching module uses +/-10.2 cm as 2 SD.
  • Corrected 2026-10-14: the page and this record said a recent study found a larger difference in "only about 3%" of children. That 3% is Zeevi et al.'s probability for one worked example, carried over by the review without its context. In Galton's published family records about one adult child in eight finished outside +/-8.5 cm (our count, 113 of 934).
  • Regression to the mean stated: children of very tall or very short parents tend to finish nearer the average than Tanner's target (Wright and Cheetham 1999, children aged 8-9; Luo et al. 1998, up to 6 cm underestimate at low mid-parental height). The calculator shows the uncorrected formula.
  • Heritability corrected: the review's "60-70% determined by parental height" replaced with Luo et al.'s primary estimate of 0.75-0.78 (Swedish population), stated as a population figure. Sex gaps of 14.4 / 13.9 / 15.8 cm and Ogata's 1990 Japanese +2 cm, later revisited, kept from the review.

Sources

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