Mid-Parental Target Height Calculator

Height unit:

Choose cm, inches, or feet and inches before entering parent heights.

Mother height:

Example: 162 cm, 64 in, or 5 ft 4 in; converted value appears below.

ft in

Father height:

Example: 176 cm, 69.3 in, or 5 ft 9 in; converted value appears below.

ft in

Child sex:

Choose Girl or Boy for the target-height formula.

Target method:

Use Classic Tanner for 13 cm, UK Simple for 12.5 cm, or Adjusted for parent-centile regression.

Range preset:

Choose ±8.5 cm, ±10.2 cm, or Custom for a different band width.

Custom half-width:

Enter 4 to 15 cm; the same half-width is applied to all methods.

Metric	Value	Copy
{{ row.label }}	{{ row.value }}
No target snapshot rows yet.

Method	Target	Band with current preset	Shift vs classic	Why it moves	Copy
{{ row.cells[0] }}	{{ row.cells[1] }}	{{ row.cells[2] }}	{{ row.cells[3] }}	{{ row.cells[4] }}
No comparison rows yet.

Focus	What it means	How to use it	Copy
{{ row.cells[0] }}	{{ row.cells[1] }}	{{ row.cells[2] }}
No interpretation rows yet.

Embed:

Customize

Include current inputs

Size

Advanced

Width

Height

Aspect ratio

Max height

Collapsible embed

Allow fullscreen

Referrer policy

Sandbox tokens

Family height gives growth measurements a context that a classroom comparison or a single growth-chart centile cannot provide. Children inherit much of their adult height potential from their biological parents, but they do not inherit an exact final number. A tall parent and a short parent can produce a wide expected range, and two parents of similar height usually produce a tighter family expectation.

Mid-parental target height is the common shorthand for that family expectation. It starts with the adult heights of the biological mother and father, adjusts for the child's sex, and turns the pair of parent heights into an estimated adult-height midpoint. The midpoint is useful because it translates family stature into the same kind of height number that appears on growth charts and clinical notes.

The midpoint is not the safest result to read alone. Pediatric growth guidance normally treats target height as a range around the midpoint because healthy children vary around family expectation. A child whose projected adult height sits close to the midpoint may still need attention if their measured growth has slowed. A child who looks short next to classmates may be growing normally if their projected adult height fits the family range.

Key ideas in mid-parental target height
Idea	Plain meaning	Common mistake
Midpoint	The family-based adult-height estimate from parent heights and child sex.	Treating it as an exact prediction.
Family band	A practical span around the midpoint for comparing projected adult height.	Ignoring the range and focusing only on one number.
Growth pattern	The child's real measurements over time, including height velocity and centile changes.	Using family height instead of serial measurements.

Several details change how the estimate should be read. Parent heights should be measured adult heights when possible, not remembered or rounded values from years ago. Sex matters because the traditional formula adjusts for the average adult height difference between males and females. Parent-height spread matters because a large difference between parents can make one simple midpoint feel more certain than it really is.

Mid-parental target height also sits beside other growth tools, not above them. Age-specific growth charts, growth velocity, pubertal timing, bone age, nutrition, chronic illness, and physical exam findings can all change the clinical meaning of a height measurement. The family target is a useful guide for asking whether a child's trajectory fits the family, but it does not diagnose growth failure or rule it out.

The estimate is most useful as a conversation frame. It helps separate a family pattern, such as familial short stature, from a pattern that looks out of range for the family. When the child's actual measurements cross centile lines, slow unexpectedly, or land well outside the family band, the family target becomes a reason to look more closely rather than a reason to ignore the trend.

How to Use This Tool:

Enter the parent heights first, then choose the sex, formula method, and family-band width that match the comparison you want to make.

Choose Height unit. You can enter heights in centimeters, inches, or feet and inches. The companion value below each parent field helps catch unit mistakes.
Enter Mother height and Father height. Each adult height must convert to 100 to 230 cm before results appear.
Select Child sex. The simple formulas add the sex offset for a boy target and subtract it for a girl target.
Choose Target method. Classic Tanner uses a 13 cm offset, UK Simple uses 12.5 cm, and Parent-Centile Adjusted uses parent adult-height z-scores with regression toward the same-sex adult median.
Open Advanced if you need a different band. 5th to 95th family span uses ±8.5 cm, 4-inch clinic span uses ±10.2 cm, and Custom half-width accepts 4 to 15 cm.
Review Target Snapshot for the selected target height, expected family band, approximate adult centile, parent spread, and method spread.
Use Formula Comparison and Interpretation Guide before sharing the result. They show whether method choice changes the midpoint and how the family band should be used.
Use the table, chart, and JSON exports only after checking the units and parent heights. Exported files are useful for discussion notes, but they are still family-height estimates.

Interpreting Results:

Selected target height is the midpoint from the chosen method. It is the easiest number to quote, but the Expected family band is usually the better comparison. A projected adult height near the midpoint is reassuring only when the child's real measurements also show steady growth.

Approx adult centile places the selected midpoint on a same-sex adult reference distribution. It is not a child growth-chart centile, and it does not say where a child sits for their current age. Use it to understand where the family target falls among adults, not to replace age-based pediatric charting.

Parent spread shows how far apart the parent heights are. A larger spread makes the family range more important because the midpoint is averaging two different adult statures. When the spread is small, the simple midpoint usually feels more stable.

Method spread shows the distance between the lowest and highest target from the three methods. Under 0.5 cm means the methods are effectively the same for the entered heights. A spread from 0.5 to under 2 cm is noticeable but usually small compared with the family band. A spread of 2 cm or more means the formula choice materially changes the midpoint.

A family-band result is not a clinical clearance. Height that falls outside the band, growth that crosses centiles, slow growth velocity, unusual puberty timing, or symptoms that suggest nutrition, endocrine, chronic disease, or genetic causes should be reviewed with a qualified clinician.

Technical Details:

Mid-parental target height is a deterministic family-height estimate. The parent heights are first put into centimeters, then the selected method converts those two adult heights into a same-sex adult target for the child. The simple methods adjust the parent average by a fixed sex offset. The adjusted method works through standard deviation scores, so very tall or very short parent pairs are pulled partway back toward the same-sex adult median.

The family band is separate from the target midpoint. Changing the band width expands or narrows the comparison span, but it does not change the midpoint. This distinction matters because clinical interpretation is usually about whether a projected adult height fits the family range, not whether it matches the midpoint exactly.

Formula Core:

The formula depends on the chosen target method and the child's sex. Heights in inches or feet and inches are converted to centimeters before these equations are applied.

\begin{array}{lcl} boy simple target & = & \frac{H_{m} + H_{f} + O}{2} \\ girl simple target & = & \frac{H_{m} + H_{f} - O}{2} \\ parent z-score & = & \frac{H - μ}{σ} \\ adjusted target & = & μ_{s} + \frac{z_{m} + z_{f}}{4} \times σ_{s} \\ adult centile & = & Φ (\frac{T - μ_{s}}{σ_{s}}) \times 100 \end{array}

Mid-parental target height symbols and constants
Symbol or value	Meaning	How it is used
`Hm`	Mother height	Entered adult height converted to centimeters.
`Hf`	Father height	Entered adult height converted to centimeters.
`O`	Simple-method sex offset	13 cm for Classic Tanner; 12.5 cm for UK Simple.
`zm`, `zf`	Parent adult-height z-scores	Used by Parent-Centile Adjusted.
`μs`, `σs`	Same-sex adult reference mean and standard deviation	Girls: 162.9 cm and 7.0 cm; boys: 176.2 cm and 7.2 cm.
`T`	Selected target midpoint	The midpoint used for the family band and approximate adult centile.
`Φ`	Normal cumulative distribution function	Converts the same-sex adult z-score into a percentile-style centile.

With a 162 cm mother, 176 cm father, and girl target, the Classic Tanner midpoint is (162 + 176 - 13) / 2 = 162.5 cm. The ±8.5 cm preset gives an expected family band of 154.0 to 171.0 cm. The UK Simple offset moves the same example by only 0.25 cm because the offset changes from 13 cm to 12.5 cm before averaging.

Mid-parental target height boundaries
Boundary	Rule	Why it matters
Parent height	Each parent must be 100 to 230 cm after conversion.	Blocks implausible adult heights before they drive the estimate.
Default family span	±8.5 cm around each method target.	Matches a tighter family-height comparison often used in pediatric growth guidance.
Clinic span	±10.2 cm around each method target.	Matches the traditional 4-inch range on either side of the midpoint.
Custom half-width	Accepted from 4 to 15 cm.	Allows a different one-sided range while avoiding an unrealistically narrow or broad band.
Method spread	Under 0.5 cm, 0.5 to under 2 cm, or 2 cm and above.	Shows whether formula choice is trivial, noticeable, or material.
Approx adult centile	Calculated from same-sex adult mean and standard deviation.	Provides adult-population context, not a pediatric growth-chart result.

Accuracy, Privacy, and Safety Notes:

The calculation is only as good as the entered parent heights and the suitability of the chosen method. Rounding each parent height by a few centimeters can move the midpoint enough to matter near a band edge, especially when comparing a projected adult height against the family range.

Use measured adult biological parent heights when possible.
Do not use the adult centile as an age-based growth-chart centile for a child.
The calculation runs in the browser from the entered values; exported tables, images, documents, and JSON should be shared only with people who should see the family-height information.
Seek clinical review when height is far below or above family expectation, growth velocity slows, centiles are crossed, puberty timing is unusual, or other health symptoms are present.

Worked Examples:

A family enters a 162 cm mother, 176 cm father, Girl, Classic Tanner, and the ±8.5 cm preset. Target Snapshot returns a selected target height near 162.5 cm and an expected family band of about 154.0 to 171.0 cm.

The same parent heights for a Boy with Classic Tanner move the midpoint to about 175.5 cm because the 13 cm sex offset is added instead of subtracted. Formula Comparison is the best place to see whether UK Simple or Parent-Centile Adjusted changes that result enough to matter.

A parent height entered as 90 cm triggers the message Parent heights should stay within a plausible adult range of 100 to 230 cm. Correcting the height or changing the unit restores Target Snapshot, Formula Comparison, Interpretation Guide, and Family Height Map.

FAQ:

Is mid-parental target height a prediction?

It is a family-height estimate, not a stand-alone prediction. It can frame growth discussions, but final adult height also depends on the child's real growth pattern, puberty timing, health, nutrition, and clinical context.

Which target method should I use?

Use Classic Tanner for the familiar 13 cm offset, UK Simple when a 12.5 cm offset is preferred, and Parent-Centile Adjusted when you want the parent z-score method shown beside the simple formulas.

Why does the family band change without changing the target?

Range preset changes only the half-width around the selected midpoint. It does not change Selected target height, Method spread, or the formula used.

What should I do if the input is rejected?

Check the selected Height unit and re-enter both parent heights. The calculation requires each parent height to land between 100 and 230 cm after conversion.

Glossary:

Mid-parental target height: A family-height midpoint estimated from biological parent adult heights and the child's sex.
Expected family band: The selected target midpoint plus and minus the chosen half-width.
Standard deviation score: A z-score showing how far a height is from a reference mean in standard deviation units.
Approx adult centile: The selected midpoint mapped to a same-sex adult reference distribution.
Growth velocity: The rate at which a child's measured height changes over time, usually read from repeated measurements.
Method spread: The distance from the lowest to highest target across the three available methods.

References:

Mid-parental Height, American Academy of Pediatrics EQIPP.
Growth Failure, Children's Mercy Kansas City.
Information for Health Staff, Royal College of Paediatrics and Child Health Digital Growth Charts.
Anthropometric Reference Data for Children and Adults: United States, 2015-2018, CDC National Center for Health Statistics.