Estimate forearm length from height, or height from forearm (ulna) length, using a published study equation for men, women or both combined.
Disclaimer: This tool provides a rough estimate only and can be inaccurate for individuals (for example due to differences in sex, age, ethnicity, body proportions, injury, or disability). It is not medical advice and is not intended for diagnosis or treatment. It has not been validated for children, pregnancy, or conditions affecting limb length. For clinical/rehabilitation or ergonomic design decisions, consult a qualified professional and use population-specific anthropometry references.
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Height to Forearm Length Formula
The calculator uses the published study equation H = a + b × U. For the combined sample, a = 57.385 and b = 4.047; male-sample values are 97.252 and 2.645, and female-sample values are 68.777 and 3.536. H and U are in centimeters. The uncited former 0.146 × height + 1.2 model has been removed.
Variables:
- U is the measured left ulna length (cm), or the algebraic line-solve result
- H is standing height or its model estimate (cm)
Units note: The study equations use centimeters. The calculator converts inches, meters and decimal feet to centimeters before calculating. The reverse expression solves the height-on-ulna line; it does not estimate the conditional mean of ulna length for a given height.
Important context: Segment-length-to-height relationships can vary by population and individual body proportions. For higher-precision work, look for population-specific anthropometry references (for example, ergonomics/anthropometric datasets used in occupational health and human factors).
The source study included Sri Lankan medical students ages 20–23. It is population-specific; no individual prediction interval is supplied here. See Ilayperuma et al. (2010). Use direct measurement for medical, forensic, ergonomic or clothing decisions.
| Height (ft/in) | Forearm Length (in) |
|---|---|
| 4’6″ | 7.761 |
| 4’8″ | 8.255 |
| 4’10” | 8.749 |
| 5’0″ | 9.243 |
| 5’2″ | 9.737 |
| 5’4″ | 10.232 |
| 5’5″ | 10.479 |
| 5’6″ | 10.726 |
| 5’7″ | 10.973 |
| 5’8″ | 11.220 |
| 5’9″ | 11.467 |
| 5’10” | 11.714 |
| 5’11” | 11.961 |
| 6’0″ | 12.208 |
| 6’1″ | 12.456 |
| 6’2″ | 12.703 |
| 6’3″ | 12.950 |
| 6’4″ | 13.197 |
| 6’5″ | 13.444 |
| 6’6″ | 13.691 |
| Calculated using U(cm) = [Height(in) × 2.54 − 57.385] ÷ 4.047, then divided by 2.54 for inches. Values may extrapolate beyond the study sample; 1 in = 2.54 cm. | |
What is Forearm Length?
This study measured left ulna length as the direct elbow-tip (olecranon) to ulnar styloid distance with the elbow fully flexed, averaging three caliper measurements. It is a defined bone-landmark measure, not every possible clothing or ergonomic forearm measurement.
How to Calculate Forearm Length from Height?
The following steps explain how to use the selected study equation:
- Choose the solve task and study group; measure height (H) or left ulna length (U).
- Use centimeters in the equations; the calculator converts supported units automatically.
- For height, apply H = a + b × U. To solve the line for U, use U = (H − a) ÷ b. This algebraic reverse is not a validated prediction of individual ulna length.
- Verify your result using the calculator above.
Example Problem:
For example, a measured left ulna length U = 25 cm gives this combined-sample height estimate:
H = 57.385 + 4.047 × 25 = 158.560 cm. Solving that same line at H = 158.560 cm returns U = 25 cm; the two directions have different statistical meanings.
