Free BSA Calculator Online
Body Surface Area using Mosteller, DuBois and Haycock formulas with drug dosage reference
Body Surface Area (BSA) is used in clinical medicine to scale drug doses — particularly chemotherapy, cardiac medications, and pediatric dosing — because it correlates better with many physiological parameters than body weight alone. This calculator computes BSA using three established formulas (Mosteller, DuBois, and Haycock) and displays drug dosage reference information.
Frequently Asked Questions
About the BSA Calculator
Body Surface Area estimation is a staple of clinical pharmacology. The concept was formalized by DuBois and DuBois in 1916, who observed that many physiological variables (cardiac output, renal function, metabolic rate) scale better with surface area than with body weight. Their original formula remains in use today alongside newer derivations.
The Mosteller formula (1987) gained widespread adoption in oncology because it's easy to compute mentally — just multiply height by weight, divide by 3600, and take the square root. The Haycock formula (1978) is particularly accurate for pediatric patients. No formula works perfectly across all body sizes and shapes, particularly in obesity where actual and estimated BSA can diverge significantly.
BSA-based drug dosing is most important for cytotoxic agents with narrow therapeutic windows, where under-dosing reduces efficacy and over-dosing causes serious toxicity. Your oncologist or pharmacist will always verify BSA calculations independently before prescribing.
Formula Used
Mosteller: BSA = √(Height(cm) × Weight(kg) / 3600)
When Should You Use This?
The BSA Calculator is ideally suited for fitness enthusiasts, healthcare professionals, and individuals monitoring their health who need to perform quick, accurate calculations related to general calculations. Use this tool when you need to verify figures, compare different scenarios, or get a precise answer without manual computation errors.
What Does The Result Mean?
The calculated metrics provide a scientifically validated baseline for your health or fitness goals. While these numbers are highly accurate based on standard medical formulas, they should serve as a guide rather than a replacement for professional medical advice.
Example Calculation
BSA calculation for a 170 cm, 70 kg adult
📥 Inputs
- Height: 170 cm
- Weight: 70 kg
🔢 Calculation Steps
- 1Mosteller: BSA = √(170 × 70 / 3600) = √(11900/3600) = √3.306 = 1.818 m²
- 2DuBois: BSA = 0.007184 × 170^0.725 × 70^0.425 = 0.007184 × 58.77 × 6.83 = 1.806 m²
- 3Haycock: BSA = 0.024265 × 170^0.3964 × 70^0.5378 = 0.024265 × 7.08 × 10.71 = 1.841 m²
- 4Average across formulas: ~1.82 m²
Limitations of this Calculator
- Formulas are based on population averages and may not perfectly reflect individuals with extreme muscle mass or atypical body compositions.
- Does not replace a physical examination or clinical diagnosis by a certified medical professional.
- Calculations cannot account for underlying metabolic conditions or genetic factors that influence individual health metrics.
How to Use the BSA Calculator
- 1Enter your values into the BSA Calculator input fields above.
- 2Review the input labels to ensure you are using the correct units.
- 3Click the "Calculate" button to get your instant result.
- 4Use the step-by-step breakdown to understand how the result was calculated.
- 5Export or copy your result to use in reports or share with others.
Tips & Best Practices
- Double-check your input units before calculating — using the wrong unit is the most common source of errors.
- Bookmark this BSA Calculator for quick access next time you need it.
- Use the share button to send your results to a colleague or save them for later reference.
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⚠️ Health Disclaimer: Results provided by this calculator are for informational and educational purposes only. They do not constitute medical advice. Always consult a qualified healthcare professional, doctor, or registered dietitian before making any health, fitness, or dietary decisions.