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BMI & BSA Calculator

Calculate Body Mass Index, Body Surface Area, Ideal Body Weight, and Adjusted Body Weight instantly.

👥 Patient Details
📏 Height
⚖ Weight
🔎 Formulas Used
BMI: weight (kg) / [height (m)]²
BSA (Mosteller): √[height (cm) × weight (kg) / 3600]
IBW (Devine): Male: 50 + 2.3 × (inches > 5ft) | Female: 45.5 + 2.3 × (inches > 5ft)
ABW: IBW + 0.4 × (Actual Weight − IBW)
📈
Enter values and calculate
Fill in height, weight, age and gender to calculate BMI, BSA, IBW and Adjusted Body Weight.
Anthropometric Calculations

How the BMI & BSA Calculator Works

Obtain Body Mass Index, Mosteller Body Surface Area, and Devine Ideal Body Weight in four simple steps.

1
Select Unit Preferences
Switch seamlessly between metric (centimeters, kilograms) and imperial (feet/inches, pounds) units with instant live conversions.
2
Enter Patient Anthropometry
Input age, biological gender, measured height, and current body weight.
3
Compute BMI & Classification
The tool computes BMI (kg/m²) and classifies the patient across Underweight, Normal, Overweight, or Obese categories with color visual cues.
4
Review BSA, IBW & ABW
Examine Body Surface Area (Mosteller formula), Ideal Body Weight (Devine formula), and Adjusted Body Weight for accurate chemotherapy and drug dosing.
Clinical Practice Benefits

Why Clinicians Rely on This Calculator

Provides multidimensional body metrics required for oncology, anesthesia, nephrology, and dietetics.

🌞
Mosteller BSA Formula
Uses the universally accepted Mosteller formula (√[height (cm) × weight (kg) / 3600]) required for chemotherapy and physiological indexation.
⚖
Devine Ideal Body Weight (IBW)
Calculates gender-specific ideal weight to prevent drug overdosing in obese patients or underdosing in critically ill ICU individuals.
📊
Visual BMI Scale Slider
Dynamic visual marker indicates exactly where the patient's BMI lands relative to WHO and Asian/Indian health cutoffs.
🔒
Client-Side Calculation
Fast, responsive execution directly on your device with complete patient confidentiality and zero latency.
BMI & BSA FAQ

Frequently Asked Questions

Answers to common questions about using the BMI and BSA calculator.

Q What is the clinical difference between BMI and BSA?

BMI (kg/m²) assesses nutritional status and weight-to-height ratio for obesity screening. Body Surface Area (m²) measures total external surface area, which correlates closely with metabolic rate, cardiac output, and glomerular filtration rate (GFR).

Q Why are lower BMI cutoffs recommended for South Asian populations?

According to WHO and Indian consensus guidelines, South Asians have higher visceral adiposity and cardiovascular/diabetic risk at lower BMI values. The cutoff for overweight in Asian Indians is ≥ 23 kg/m² (vs 25 Western) and obesity is ≥ 25 kg/m² (vs 30 Western).

Q When should doctors use Adjusted Body Weight (ABW)?

When a patient's actual weight exceeds 120% of their Ideal Body Weight (IBW), hydrophillic medications (such as aminoglycosides or vancomycin) do not distribute fully into adipose tissue. Adjusted Body Weight (ABW = IBW + 0.4 × [Actual − IBW]) provides a safer dosing weight.

Q Which formula is used for BSA calculation?

This tool implements the Mosteller formula (BSA = √[Height (cm) × Weight (kg) / 3600]), which is the standard formula utilized by hospital oncology protocols and clinical calculators worldwide.

Track patient BMI over visits? ClinicKare automatically records and charts BMI, weight, and vitals across all patient visits.
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