By Zencalcy Editorial TeamLast reviewed About us
When a person cannot stand, standing height can be estimated from knee height and age. The Chumlea equations are widely used in older adults and in long-term care. The estimate is less precise than a direct measurement and should be documented as an estimate.
Estimate standing height from knee height when standing is not possible.
Men: height(cm) = 64.19 − 0.04 × age + 2.02 × knee height(cm) Women: height(cm) = 84.88 − 0.24 × age + 1.83 × knee height(cm)
These are the Chumlea knee-height equations for adults. They were derived in older populations and are most reliable in that group. Use the same technique for repeat measurements and record that the value is estimated.
| Symbol | Meaning |
|---|---|
| Knee height | Distance from the sole to the anterior thigh above the knee. |
| Age | Age in years. |
| Height | Estimated standing height in centimetres. |
84.88 − 0.24 × 78 + 1.83 × 48 = 84.88 − 18.72 + 87.84 = 154.0 cm. A man of the same age with 52 cm knee height would estimate 64.19 − 3.12 + 105.04 = 166.1 cm.
Height is used to calculate BMI, estimate renal function, size ventilator settings and set nutrition targets. Losing that input in a bedridden patient can distort every downstream calculation. Knee height works because the long bones of the lower leg change little with age and are easy to reach in a supine patient. The Chumlea equations combine knee height with age to account for the slight shortening of stature that occurs with ageing. The trade-off is precision: a tape measurement around a flexed knee has more error than a stadiometer reading. Best practice is to measure carefully, record the method in the chart, and avoid mixing estimated and measured heights in a trend. If a patient's height is needed for a high-stakes calculation, the clinical team should agree on the method and use it consistently.
Continue with the ABSI Calculator (A Body Shape Index), Adjusted Body Weight Calculator, or the BAI Calculator (Body Adiposity Index) — or browse more body measurements tools and all health calculators.
Also see the Body Fat Calculator.
Knee height is less affected by contractures and can be measured reliably in a supine patient. Arm span requires the arms to be extended, which is not always possible.
Every result is a screening estimate from published anthropometric equations, not a diagnosis or a measurement of body composition. Tape measurements should be taken snugly against the skin without compressing it, at the landmarks named in each tool. Equations were derived in specific populations and can be less accurate for athletes, older adults, children, pregnant people and people with significant oedema.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
Content updated: September 2026