The body-segment data and formula behind the correction, with citations.
Correcting BMI for limb loss requires an estimate of how much of total body mass a given limb segment represents. This calculator uses body-segment weight percentages drawn from classic biomechanics anthropometry research — most notably the work of David A. Winter and later refinements building on Dempster's original cadaver-based segment studies — which remain the standard reference tables used in prosthetics, rehabilitation, and biomechanics research for estimating segmental body mass.
| Amputation level | % of total body mass (single limb) |
|---|---|
| Above-knee (transfemoral) | 9.9% |
| Below-knee (transtibial) | 4.4% |
| Foot / partial foot | 1.5% |
| Above-elbow (transhumeral) | 3.35% |
| Below-elbow (transradial) | 2.3% |
| Hand / partial hand | 0.7% |
Mixed and bilateral amputations are handled by summing the applicable percentage for each affected limb independently (e.g. a below-knee amputation on one leg plus an above-knee amputation on the other sums to 4.4% + 9.9% = 14.3% of total body mass).
missing_fraction = sum(segment_% for each affected limb) / 100
estimated_full_weight = current_weight / (1 − missing_fraction)
corrected_BMI = estimated_full_weight / (height_m)²
The logic: current measured weight reflects a body with the limb segment(s) missing. Dividing by (1 − missing_fraction) estimates what total body weight would be if that mass were restored. BMI is then recalculated using that estimated full-body weight against pre-amputation height, following the standard BMI formula.
Segment weight percentages are population averages derived from biomechanics research, not individualized measurements. Actual body composition varies by age, sex, body type, residual limb length within a given amputation level, and other factors not captured by a single percentage. Corrected BMI should be understood as a better estimate than uncorrected BMI — not an exact clinical measurement — and is intended to support, not replace, individualized clinical assessment.