Body Surface Area (BSA) Calculator (USA)
Calculate BSA for accurate medication dosing and medical assessments. For educational purposes only.
How BSA is Calculated
Body Surface Area is calculated using the DuBois formula:
This calculation provides a more accurate dosing parameter than weight alone, particularly for chemotherapy and other critical medications.
- Height Units: Centimeters (cm)
- Weight Units: Kilograms (kg)
- BSA Units: Square meters (m²)
- Normal Range: 1.6-2.0 m² for adults
BSA Calculator
BSA Visualization
BSA Value
BSA Applications
BSA is used for:
- Chemotherapy dosing
- Cardiac index calculation
- Glomerular filtration rate
- Metabolic rate estimation
- Thyroid function tests
- Medication adjustments
BSA calculations are for reference only. Always confirm with healthcare professionals before medication administration.
- Verify all measurements
- Use appropriate units
- Consider patient factors
- Follow institutional protocols
- Document all calculations
Understanding BSA
Body Surface Area (BSA) is the calculated or estimated measurement of the total surface area of a human body. It's a more physiologically relevant measure than body weight alone for determining metabolic mass and drug dosing.
DuBois Formula (Most Common)
Alternative Formulas
- Mosteller: √(Height×Weight/3600)
- Haycock: 0.024265×Height^0.3964×Weight^0.5378
- Gehan & George: 0.0235×Height^0.42246×Weight^0.51456
- Chemotherapy dosing (most critical)
- Cardiac output assessment
- Kidney function evaluation
- Metabolic studies
- Thyroid medication adjustment
- Anticoagulant dosing
- Immunosuppressant therapy
BSA Reference Values
| Age Group | Height (cm) | Weight (kg) | BSA (m²) | Typical Use |
|---|---|---|---|---|
| Neonate | 50 | 3.5 | 0.23 | Pediatric dosing |
| Infant (1 yr) | 75 | 10 | 0.45 | Pediatric dosing |
| Child (5 yrs) | 110 | 18 | 0.71 | Pediatric dosing |
| Child (10 yrs) | 140 | 32 | 1.07 | Pediatric dosing |
| Adult Female | 163 | 60 | 1.62 | Standard dosing |
| Adult Male | 178 | 70 | 1.87 | Standard dosing |
BSA Calculation Quiz
Select the correct formula:
The correct answer is a) √(Height × Weight / 3600). The DuBois formula calculates BSA as the square root of (Height in cm × Weight in kg) divided by 3600.
Memorize the standard DuBois formula for BSA calculation.
Calculate using the DuBois formula:
The correct answer is b) 1.81 m². Calculation: √(170 × 70 / 3600) = √(11900 / 3600) = √3.306 = 1.81 m².
Practice applying the BSA formula with real values.
Select the most important application:
The correct answer is b) Chemotherapy agents. BSA is most critically used for dosing chemotherapy drugs because of their narrow therapeutic index and potential for severe toxicity.
Understand the most important clinical applications of BSA.
Q&A
Q: Why is BSA preferred over weight for certain medications?
A: BSA is preferred over weight for certain medications because it provides a more accurate reflection of:
Physiological Relevance:
- Metabolic mass (not just fat vs. lean tissue)
- Organ perfusion rates
- Drug clearance mechanisms
- Cellular mass for cytotoxic drugs
For example, in chemotherapy, using weight alone can lead to overdosing thin patients and underdosing obese patients, while BSA provides a more physiologically appropriate dosing metric.
Q: Are there limitations to using BSA for dosing?
A: Yes, BSA has several limitations:
Known Limitations:
- Does not account for body composition (muscle vs. fat)
- May not reflect organ function in elderly patients
- Does not consider genetic factors affecting drug metabolism
- May not be appropriate for all drug classes
- Does not account for disease states affecting drug distribution
Some institutions now use weight-based dosing or therapeutic drug monitoring instead of BSA for certain medications, though BSA remains the standard for most chemotherapeutic agents.