Mid-parental height is the average of both parents' heights, adjusted for the child's sex: add 5 inches (13 cm) for a boy or subtract 5 inches for a girl, then divide by 2. The result is the child's genetic "target height." In Tanner's widely used method, most healthy children, roughly 95 in 100, end up within about 3.3 inches (8.5 cm) above or below that target.
How to use the mid-parental height calculator
- Choose the child's sex.
- Enter the father's and the mother's height. Measured heights are better than remembered ones; doctors are advised to measure parents rather than take their word for it.
- Read the target height and the range around it.
That's all it needs. It does not use the child's age or current height, which is both its strength (it works at any age) and its main limit.
The midparental height formula
This is the Tanner method, published in 1970 and still used by pediatricians:
- Boys: (father's height + mother's height + 5 in) ÷ 2. In metric, add 13 cm.
- Girls: (father's height + mother's height − 5 in) ÷ 2. In metric, subtract 13 cm.
- Target range: about ±3.3 in (±8.5 cm), which corresponds to two standard deviations.
The 5 inches (13 cm) reflects the average height difference between men and women.
Worked example: mom is 5'4", dad is 5'10"
This is one of the most common questions people search, so here is the full math. Mom is 5'4" (64 in, about 163 cm) and dad is 5'10" (70 in, about 178 cm).
| Boy | Girl | |
|---|---|---|
| Calculation | (70 + 64 + 5) ÷ 2 | (70 + 64 − 5) ÷ 2 |
| Target height | 69.5 in = 5'9.5" (about 177 cm) | 64.5 in = 5'4.5" (about 164 cm) |
| Likely range (±3.3 in) | 5'6" to 6'1" (168 to 185 cm) | 5'1" to 5'8" (155 to 172 cm) |
So a son of these parents would most likely end up between 5'6" and 6'1", with 5'9.5" as the middle estimate, close to the average US man. A daughter would most likely end up between 5'1" and 5'8".
Can you be taller than your parents?
Yes, and plenty of people are. Each child gets a different combination of height-related gene variants from their parents, so brothers and sisters often finish several inches apart. About 80% of the differences in height between people is inherited; the rest comes from things like nutrition and health during childhood.
The formula can also run a little low when parents are older. In a 2024 study of large families, where the parents were measured at around age 60, children averaged about 1 inch (2.7 cm) taller than the standard formula predicted. Almost all of that gap disappeared once the researchers corrected for the height adults slowly lose with age, which starts around 30. With younger parents the effect is smaller, and the study involved one specific population, so the exact numbers may not apply to everyone.
Regression to the mean: why very tall or short parents are harder to predict
Children of very tall parents tend to end up somewhat shorter than the formula suggests, and children of very short parents somewhat taller. This pattern is called regression to the mean, and the basic Tanner formula doesn't account for it. Researchers have proposed corrected formulas for this reason.
In practice, if both parents are much taller or shorter than average, read the target as a slight overestimate (tall parents) or underestimate (short parents). For example, a 6'3" father and a 5'10" mother give a son a target of 6'3". He may well get there, but on average sons of such tall parents fall a little below the formula.
Mid-parental height vs. our height calculator
Mid-parental height only looks at the parents. Our height calculator also uses the child's own growth curve on the CDC charts and blends the two: about half and half in childhood, then mostly the child's curve by 16 or 17. For a teen, that blended estimate is usually more informative. Teens who want a guided version can take the How Tall Will I Be? quiz, and the full method is on our methodology page.
Mayo Clinic notes there is no sure way to predict a child's adult height. Puberty timing in particular can move a child above or below the family target for years, as happens with late bloomers.
When to see a doctor
Doctors use mid-parental height to judge whether a child's growth fits the family. It is worth a checkup if a child's growth curve points well below the family target, if growth slows or drops across percentile lines (you can check with the height percentile calculator), or if puberty has not started by about 14 in boys or 13 in girls.
The takeaway
The mid-parental height calculator gives a quick genetic target and a realistic range. Use it as a starting point, then follow the child's actual growth over time, which tells you more with every passing year.
Frequently asked questions
Is the mid-parental height formula accurate?
It is a useful target, not a forecast. Tanner's range of about 3.3 inches (8.5 cm) either side is meant to cover most healthy children, roughly 95 out of 100. It works less well for children of very tall or very short parents, and it ignores how the child is actually growing.
Why do you add 5 inches for boys and subtract 5 for girls?
Men are on average about 5 inches (13 cm) taller than women. The formula adjusts for that so that a mother's height can be compared with a son's and a father's height with a daughter's, then averages the two.
What if I only know one parent's height?
The mid-parental formula needs both parents. Without them, our height calculator can still estimate adult height from the child's own position on the CDC growth chart, which is the better predictor for teens anyway.
Do both parents' heights count equally?
In the formula, yes. In real life, each child inherits a different mix of the many gene variants that affect height from both parents, which is why brothers and sisters can end up at quite different heights.
At what age is mid-parental height most useful?
It is most useful in younger children, whose current height says little about adult height. Tanner's original parent-adjusted standards were built for ages 2 to 9. In the teen years, the child's own growth curve becomes more informative, which is why our main calculator relies on it more with age.
Sources
- Height Potential: A Child's Target Height Based on Midparental Height — MSD Manuals (Merck Manual Professional)
- Standards for children's height at ages 2-9 years allowing for heights of parents (Arch Dis Child, 1970) — PubMed
- Accurate Prediction of Children's Target Height from Their Mid-Parental Height (Children, 2024) — PubMed Central
- The calculation of target height reconsidered (Horm Res, 2003) — PubMed
- Child growth: Can you predict adult height? — Mayo Clinic
- Is height determined by genetics? — MedlinePlus Genetics (NIH)
- Evaluation of Short and Tall Stature in Children — American Family Physician (AAFP)
Updated 2026-11-05. How our calculators work · Editorial policy