Standard BMI doesn't account for missing limb mass, so it reads artificially low after amputation. This tool applies validated body-segment correction to give you an accurate, weight-adjusted BMI.
The correction, explained
Body Mass Index (BMI) is calculated from total body weight divided by height squared. It assumes an intact body — but after amputation, a meaningful percentage of total body mass is missing. A below-knee amputation removes roughly 4.4% of total body weight; an above-knee amputation removes about 9.9%. Bilateral amputations roughly double that figure.
Because that mass is gone, the weight measured on a scale is lower than it would be with the limb intact — which pulls standard BMI down, sometimes into a range that looks "underweight" or falsely "normal" when a person's actual body composition would place them elsewhere on the scale entirely.
This tool uses published body-segment weight tables (based on Winter/Dempster biomechanics research) to estimate what total body weight would be if the missing limb segment were still present, then recalculates BMI from that estimate. This gives clinicians and patients a more accurate reference point for weight-related conversations — nutrition, cardiovascular risk, prosthetic fitting, and rehabilitation planning.
Is corrected BMI more accurate than standard BMI for everyone?
No — it's specifically intended for people with limb loss. For non-amputees, standard BMI calculations are already accurate to the assumptions built into the formula.
What amputation levels does this support?
Above-knee (transfemoral), below-knee (transtibial), above-elbow (transhumeral), below-elbow (transradial), foot, and hand amputations, for unilateral or bilateral limb loss.
Should I use this instead of talking to my care team?
No. This tool is meant to support informed conversations with your physical therapist, occupational therapist, or physician — not replace their assessment.
Where do the correction percentages come from?
They're derived from published anthropometric body-segment weight research (Winter/Dempster segment tables), which estimate what percentage of total body mass different limb segments typically represent.