Body Surface Area Calculator
Calculate your body surface area using different medical formulas
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Age (Optional)
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Measurement System
Preferred Formula
Height
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Weight
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Your Body Surface Area Results
Calculated using different medical formulas
1.85
m²
Body Surface Area calculated using Mosteller formula
1.2 m²
2.5 m²
1.85 m²
BSA Formula Comparison
√(H×W/3600)
1.85
Mosteller
Most common
0.20247×H^0.725×W^0.425
1.83
Du Bois
-1.1%
0.024265×H^0.3964×W^0.5378
1.87
Haycock
+1.1%
0.0235×H^0.42246×W^0.51456
1.86
Gehan
+0.5%
| Formula | Value (m²) | Difference | Notes |
|---|---|---|---|
| Mosteller √(H×W/3600) |
1.85 | Baseline | Most common |
| Du Bois 0.20247×H^0.725×W^0.425 |
1.83 | -1.1% | Historical |
| Haycock 0.024265×H^0.3964×W^0.5378 |
1.87 | +1.1% | All ages |
| Gehan 0.0235×H^0.42246×W^0.51456 |
1.86 | +0.5% | Chemotherapy |
Medical Applications of BSA
Medication Dosing
Used to calculate precise doses for chemotherapy, antibiotics, and other medications that require body size adjustment.
Example: Chemotherapy dose = BSA × Standard dose
Fluid Management
Helps determine fluid requirements, especially in critical care, burn patients, and pediatric medicine.
Example: Maintenance fluids = 1500 mL/m²/day
Clinical Research
Normalizes physiological parameters like cardiac output, glomerular filtration rate, and metabolic rate for comparisons.
Example: Cardiac index = Cardiac output ÷ BSA
Fitness Assessment
Used in sports medicine and fitness to calculate VO₂ max, calorie expenditure, and other performance metrics.
Example: VO₂ max = Maximum oxygen uptake ÷ BSA
BSA Reference Ranges by Age and Gender
| Age Group | Male BSA Range (m²) | Female BSA Range (m²) | Average BSA | Notes |
|---|---|---|---|---|
| Newborn | 0.20 - 0.25 | 0.19 - 0.24 | 0.22 | Rapid growth phase |
| 1 year | 0.45 - 0.55 | 0.43 - 0.53 | 0.49 | Triples in first year |
| 5 years | 0.70 - 0.85 | 0.68 - 0.82 | 0.76 | Steady growth |
| 10 years | 1.10 - 1.30 | 1.05 - 1.25 | 1.18 | Pre-puberty |
| 15 years | 1.60 - 1.90 | 1.45 - 1.70 | 1.65 | Growth spurt |
| Adult (20-40) | 1.80 - 2.20 | 1.60 - 1.90 | 1.85 | Stable period |
| Middle Age (40-60) | 1.90 - 2.30 | 1.70 - 2.00 | 1.95 | May increase with weight gain |
| Senior (60+) | 1.80 - 2.20 | 1.60 - 1.90 | 1.85 | May decrease with height loss |
About Body Surface Area (BSA)
Body Surface Area is the total surface area of the human body. It's a crucial measurement in medicine because many physiological processes, metabolic rates, and medication dosages correlate better with BSA than with body weight alone.
Common BSA Calculation Formulas
| Formula | Equation | Year | Population | Accuracy | Common Use |
|---|---|---|---|---|---|
| Mosteller | √(height × weight / 3600) | 1987 | Adults & Children | ±5% | Clinical practice, oncology |
| Du Bois & Du Bois | 0.20247 × H^0.725 × W^0.425 | 1916 | Adults | ±2% | Historical, research |
| Haycock | 0.024265 × H^0.3964 × W^0.5378 | 1978 | Infants to Adults | ±1% | Pediatrics, all ages |
| Gehan & George | 0.0235 × H^0.42246 × W^0.51456 | 1970 | Adults | ±3% | Oncology, chemotherapy |
| Boyd | 0.0003207 × H^0.3 × W^(0.7285-0.0188×logW) | 1935 | All ages | ±2% | Comprehensive studies |
How BSA Formulas Differ
- Mosteller: Simplest to calculate, widely accepted in clinical practice
- Du Bois: First scientific formula, basis for many later formulas
- Haycock: Most accurate across all age groups including children
- Gehan & George: Developed specifically for chemotherapy dosing
- Boyd: Most complex but very accurate, used in research settings
Clinical Applications of BSA
| Medical Field | Application | Formula Typically Used | Importance |
|---|---|---|---|
| Oncology | Chemotherapy dosing | Mosteller or Gehan | Critical - affects treatment efficacy and toxicity |
| Cardiology | Cardiac index calculation | Du Bois or Mosteller | Essential for hemodynamic monitoring |
| Nephrology | Glomerular filtration rate normalization | Mosteller | Standardizes kidney function assessment |
| Pediatrics | Medication dosing, fluid management | Haycock or Boyd | Critical for safe pediatric dosing |
| Burn Care | Burn size estimation, fluid resuscitation | Mosteller | Determines treatment intensity |
| Anesthesiology | Anesthetic drug dosing | Mosteller | Ensures proper sedation levels |
Limitations of BSA Calculations
- Formulas assume "average" body proportions - may be less accurate for extreme body types
- Does not account for body composition (muscle vs. fat distribution)
- May overestimate BSA in obese individuals and underestimate in very lean individuals
- Age-specific formulas are more accurate for children and elderly
- Different formulas can produce significantly different results (±10-15%)
- BSA does not perfectly correlate with all physiological processes
Important Medical Considerations
- BSA calculations are estimates - not exact measurements
- For medical treatment, always use the formula specified by treatment protocols
- In clinical settings, BSA should be calculated to two decimal places (e.g., 1.85 m²)
- For chemotherapy, BSA is often capped at 2.0 m² regardless of actual calculation
- Pediatric BSA calculations require age-appropriate formulas
- Always verify calculations and consult with healthcare professionals for medical decisions
- BSA should be recalculated if patient's weight changes significantly during treatment