Estimate adult height from bone age, chronological age, current height, and parent heights, with height conversion in cm, ft, and inches.
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Bone Age Height Formula
The bone age height calculator uses three related methods: a bone-age predicted adult height estimate, a parents-only mid-parental height estimate, and a height converter.
PAH = H / MF
MF = MF_0 + ((BA - BA_0) / (BA_1 - BA_0)) * (MF_1 - MF_0)
ParentAdjusted = 0.75 * PAH + 0.25 * MPH
MPH_male = (M + F + 13) / 2
MPH_female = (M + F - 13) / 2
TypicalRange = MPH +/- 8.5
BMI = kg / m^2
cm = (ft * 12 + in) * 2.54
totalInches = cm / 2.54
- PAH = predicted adult height in centimeters
- H = current height in centimeters
- MF = skeletal maturity fraction for the selected sex and bone age
- BA = bone age in years
- BA0, BA1 = the two table bone ages around the entered bone age
- MF0, MF1 = the maturity fractions for those surrounding bone ages
- ParentAdjusted = estimate that blends the bone-age estimate with the mid-parental target
- MPH = mid-parental height target in centimeters
- M = mother's height in centimeters
- F = father's height in centimeters
- kg = weight in kilograms
- m = height in meters
- ft = feet
- in = inches
In the bone age predictor mode, your current height is divided by the skeletal maturity fraction for the entered bone age and sex. If the bone age falls between two whole-year table values, the maturity fraction is interpolated between them.
If both parent heights are entered, the calculator also finds the mid-parental target height and blends it with the bone-age estimate. The displayed parent-adjusted estimate is 75% bone-age estimate and 25% mid-parental target.
In the parents-only mode, the calculator uses the mid-parental height formula. For a male child it adds 13 cm before dividing by 2. For a female child it subtracts 13 cm before dividing by 2. The typical range shown is the target height plus or minus 8.5 cm.
In the height converter mode, centimeters are converted to total inches, then split into feet and remaining inches. Feet and inches are converted back to centimeters by converting the full height to total inches and multiplying by 2.54.
Skeletal Maturity Values and Bone Age Status
The bone-age estimate depends heavily on the skeletal maturity fraction. The table below shows selected values used by the calculator.
| Bone age | Male maturity | Female maturity |
|---|---|---|
| 8 years | 78.0% | 82.5% |
| 10 years | 83.5% | 88.5% |
| 12 years | 89.5% | 95.0% |
| 14 years | 95.5% | 99.0% |
| 16 years | 99.0% | 100.0% |
| Bone age compared with chronological age | Meaning in the calculator result |
|---|---|
| Bone age is higher | Skeletal maturity is advanced compared with calendar age. |
| Bone age is about the same | Skeletal maturity is close to chronological age. |
| Bone age is lower | Skeletal maturity is delayed compared with calendar age. |
Examples
Example 1: Bone-age height prediction with parent adjustment
A male child has a bone age of 12 years, chronological age of 12 years, current height of 145 cm, mother height of 165 cm, and father height of 180 cm.
- Male maturity fraction at bone age 12 = 0.895
- Bone-age predicted adult height = 145 / 0.895 = 162.0 cm
- Mid-parental target = (165 + 180 + 13) / 2 = 179.0 cm
- Parent-adjusted estimate = 0.75 × 162.0 + 0.25 × 179.0 = 166.3 cm
Example 2: Parents-only estimate
A female child has a mother who is 160 cm and a father who is 178 cm.
- Mid-parental target = (160 + 178 - 13) / 2 = 162.5 cm
- Typical range = 162.5 ± 8.5 cm
- Typical range = 154.0 cm to 171.0 cm
FAQ
Is a bone age height estimate exact?
No. A bone age height estimate is only an estimate based on current height, skeletal maturity, sex, and optionally parent heights. Growth can be affected by puberty timing, nutrition, medical conditions, hormones, and measurement error. A bone age result should not be treated as a diagnosis.
Why does bone age matter more than chronological age?
Chronological age is the child's calendar age. Bone age describes skeletal maturity. Two children can both be 12 years old, but one may have bones that look closer to 10 years and another closer to 14 years. The child with a lower bone age may have more growth remaining, while the child with a higher bone age may be closer to adult height.
Why does the parent-adjusted result differ from the bone-age estimate?
The bone-age estimate uses the child's current height and skeletal maturity. The parent-adjusted result also includes genetic height tendency from the parents. If the mid-parental target is higher than the bone-age estimate, the adjusted result moves upward. If it is lower, the adjusted result moves downward.
