Bmi Calculator for Amputations

Amputee BMI Calculator

Select Missing Limbs

Check all that apply to calculate your adjusted BMI correctly.

Adjusted Body Mass Index:

0.0

Normal

function calculateAmputeeBMI() { var heightCm = parseFloat(document.getElementById('height_cm').value); var weightKg = parseFloat(document.getElementById('weight_kg').value); var checkboxes = document.getElementsByClassName('limb-check'); if (!heightCm || !weightKg || heightCm <= 0 || weightKg <= 0) { alert('Please enter valid height and weight values.'); return; } var totalAdjustment = 0; for (var i = 0; i = 1) totalAdjustment = 0.99; // Estimated original body weight: Current Weight / (1 – sum of limb percentages) var estimatedWeight = weightKg / (1 – totalAdjustment); // Height in meters var heightM = heightCm / 100; // Standard BMI formula: Weight (kg) / [Height (m)]^2 var adjustedBMI = estimatedWeight / (heightM * heightM); var category = ""; var color = ""; if (adjustedBMI = 18.5 && adjustedBMI = 25 && adjustedBMI < 30) { category = "Overweight"; color = "#e67e22"; } else { category = "Obese"; color = "#c0392b"; } document.getElementById('bmi-value').innerText = adjustedBMI.toFixed(1); document.getElementById('bmi-category').innerText = category; document.getElementById('bmi-category').style.color = color; document.getElementById('est-weight-info').innerHTML = "Estimated Pre-Amputation Weight: " + estimatedWeight.toFixed(1) + " kg(Used for adjustment based on a " + (totalAdjustment * 100).toFixed(1) + "% limb weight loss)"; document.getElementById('bmi-result-container').style.display = "block"; }

Why Amputees Need an Adjusted BMI

The standard Body Mass Index (BMI) calculation is a simple ratio of weight to height. However, for individuals who have undergone limb amputations, this standard formula is often inaccurate. Because a portion of the body's natural mass is missing, the "Current Weight" recorded on a scale does not reflect the total metabolic mass or the proportions intended for a person of that height.

Using a standard BMI calculator after an amputation usually results in an "Underweight" or "Lower" classification than is reality, which can lead to misdiagnosis in nutritional assessments or medical risks. The Amputee BMI Calculator uses the Amputee Weight Adjustment Formula to estimate what your weight would be with all limbs present, providing a more accurate reflection of your health status.

How the Calculation Works

This calculator utilizes the estimated weight percentages for specific body parts, derived from medical anthropometric data. To find the adjusted BMI, we first calculate the Estimated Pre-amputation Weight:

Estimated Weight = Current Weight / (1 – % Missing Limbs)

Once the estimated total weight is found, the standard BMI formula is applied: Weight (kg) / [Height (m)]².

Standard Limb Weight Percentages

Health professionals typically use the following percentages to estimate the weight of missing limbs:

• Hand: 0.7%
• Forearm: 1.6%
• Upper Arm: 2.7%
• Entire Arm: 5.0%
• Foot: 1.5%
• Below the Knee (BKA): 5.9%
• Above the Knee (AKA): 10.1%
• Entire Leg: 16.0%

Practical Example

Imagine a person who is 180cm tall and currently weighs 75kg, but has had an entire leg amputated (16.0% of body weight).

1. Standard BMI: 75 / (1.8 * 1.8) = 23.1 (Normal)
2. Adjustment Factor: 1 – 0.16 = 0.84
3. Estimated Weight: 75 / 0.84 = 89.3 kg
4. Adjusted BMI: 89.3 / (1.8 * 1.8) = 27.6 (Overweight)

In this case, the standard BMI would suggest the individual is at a healthy weight, whereas the adjusted BMI reveals they are actually in the overweight category, which may change their clinical care plan or nutritional goals.

Medical Disclaimer: This calculator is for educational purposes only. BMI is a screening tool, not a diagnostic of the body fatness or health of an individual. Always consult with a healthcare professional or registered dietitian for a comprehensive health assessment.