Height and weight are needed for nutrition screening, drug dosing and ventilator settings, but they are hard to measure when a patient cannot stand. Long-bone lengths change little through adult life, so they make good stand-ins for height.
How to use the Height and Weight Estimation for Bedridden Patients
- Sex
- Age
- Ethnicity (for knee-height equations)
- Height method
- Knee height
- Ulna length
- Demi-span
- Arm span
- Mid-arm circumference
Results update as you type, and every field accepts the units shown in its menu.
How it works
Choose a measurement method and enter the length. Knee height is measured on the left leg with knee and ankle at 90°, from the heel to the top of the knee. Ulna length runs from the elbow point to the wrist bone. Demi-span runs from the sternal notch to the web between the middle and ring fingers. For weight, add mid-arm circumference measured halfway between shoulder and elbow.
Tips
- Measure in the morning, before eating, wearing light clothing and without shoes.
- Use a flexible, non-stretch tape held snug but not tight, kept level all the way round.
- Take each measurement twice and use the average; small tape errors change ratios a lot.
- Track the trend over weeks rather than reacting to a single reading.
Common mistakes to avoid
- Measuring the waist at the belly button for every formula – some methods use the narrowest point or the top of the hip bone.
- Mixing inches and centimetres between measurements.
- Treating a formula estimate as a precise body-composition scan.
Inputs explained
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Age | In years |
| Ethnicity (for knee-height equations) | Choose one: White, Black |
| Height method | Choose one: Knee height (Chumlea), Ulna length (BAPEN MUST), Demi-span (Bassey), Arm span |
| Knee height | Units: cm, in, m, ft, mm |
| Ulna length | Units: cm, in, m, ft, mm |
| Demi-span | Units: cm, in, m, ft, mm |
| Arm span | Units: cm, in, m, ft, mm |
| Mid-arm circumference | Units: cm, in, m, ft, mm |
Example values
How the main result changes when Age changes and everything else stays at the example values above:
| Age (years) | Estimated height (cm) |
|---|---|
| 35 | 169.6 |
| 52.5 | 169.6 |
| 70 | 169.6 |
| 87.5 | 169.6 |
| 105 | 169.6 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Knee height (Chumlea): white men 71.85 + 1.88·KH; black men 73.42 + 1.79·KH; white women 70.25 + 1.87·KH − 0.06·age; black women 68.10 + 1.86·KH − 0.06·ageUlna (MUST): men < 65 y H = 79.2 + 3.60·U; ≥ 65 y 87.5 + 3.11·U; women < 65 y 96.3 + 2.74·U; ≥ 65 y 79.7 + 3.26·UDemi-span (Bassey): men 1.40·DS + 57.8; women 1.35·DS + 60.1Weight (Ross): white men 1.19·KH + 3.21·MAC − 86.82; black men 1.09·KH + 3.14·MAC − 83.72; white women 1.01·KH + 2.81·MAC − 66.04; black women 1.24·KH + 2.97·MAC − 82.48 (cm, kg)Worked example
Inputs — Sex: Male; Age: 70 years; Ethnicity (for knee-height equations): White; Height method: Knee height (Chumlea); Knee height: 52 cm; Mid-arm circumference: 28 cm.
Results — Estimated height = 169.6 cm; Estimated weight (Ross, knee height + MAC) = 64.9 kg; Estimated BMI = 22.6.
Key terms
- Knee height
- Distance from the heel to the top of the knee with the knee bent at 90°.
- Demi-span
- Distance from the sternal notch to the finger web between the middle and ring fingers.
- MAC
- Mid-upper-arm circumference.
Frequently asked questions
Which method is most accurate?
Knee height and ulna length are the most widely validated; arm span over-estimates height in some older people.
Why is age in the equations?
Older adults lose height through spinal compression while bone lengths stay the same.
How accurate is the weight estimate?
Typically within about ±8 kg, so use a bed or chair scale when available.
What formula does the Height and Weight Estimation for Bedridden Patients use?
Knee height (Chumlea): white men 71.85 + 1.88·KH; black men 73.42 + 1.79·KH; white women 70.25 + 1.87·KH − 0.06·age; black women 68.10 + 1.86·KH − 0.06·age.