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Body Surface Area Calculator

Calculate body surface area (BSA) using Mosteller, DuBois & DuBois, Haycock, and Boyd formulas. Used in medical dosing and clinical settings.

BSA is used in clinical settings for drug dosing, especially chemotherapy. Consult a healthcare professional for all medical decisions.

What is Body Surface Area Calculator?

Body surface area (BSA) is the total skin area of the human body expressed in square metres. It is used in clinical medicine primarily to calculate drug doses — particularly in chemotherapy, where dosing by BSA is more accurate than dosing by body weight alone because BSA correlates better with cardiac output, kidney filtration rate, and metabolic rate. This calculator computes BSA using four validated formulas: Mosteller (the most widely used in clinical practice), DuBois & DuBois (the original 1916 formula), Haycock (preferred for paediatric patients), and Boyd.

How to use

  1. 1 Enter your height and select centimetres or inches.
  2. 2 Enter your weight and select kilograms or pounds.
  3. 3 The main result shows your BSA using the Mosteller formula.
  4. 4 The table below shows results from all four formulas side by side.
  5. 5 Share the result with your healthcare provider — do not use it to self-determine medication doses.

Formula

Mosteller: BSA = √(height(cm) × weight(kg) / 3600). DuBois: BSA = 0.007184 × height^0.725 × weight^0.425. Haycock: BSA = 0.024265 × height^0.3964 × weight^0.5378. Boyd: BSA = 0.0003207 × height^0.3 × (weight×1000)^(0.7285 − 0.0188×log10(weight×1000)).

Example calculation

For a person 170 cm tall and 70 kg: Mosteller = 1.820 m², DuBois = 1.823 m², Haycock = 1.811 m², Boyd = 1.813 m². All four formulas typically agree within 1–3%, confirming the robustness of BSA estimation.

Frequently asked questions

Why is BSA used for drug dosing?

BSA correlates better with several physiological parameters than body weight, including cardiac output, kidney filtration rate, and metabolic rate. This makes it a more reliable basis for dosing drugs that have a narrow therapeutic window, such as chemotherapy agents where an overdose can be fatal.

Which BSA formula is most accurate?

The Mosteller formula is the most widely used in clinical practice due to its simplicity and good accuracy. The DuBois & DuBois formula was the original and remains common. Haycock is generally preferred for paediatric and neonatal patients. Boyd is accurate across a wide range of body sizes. No single formula is definitively best for all populations.

What is the average BSA for adults?

The average BSA for adult males is approximately 1.9 m² and for adult females approximately 1.6 m². These values serve as a reference point in some drug dosing protocols that use a standard dose calculated for an 'average' patient.

Can I use this to calculate my own drug dose?

No. Drug dosing based on BSA must always be calculated and verified by a qualified healthcare professional. This tool is for educational and informational purposes only. Never adjust medication doses based on self-calculated BSA.

Does BSA change with weight loss or gain?

Yes. BSA is directly influenced by both height and weight, so significant changes in body weight will change your BSA. Since most adults have a stable height, weight changes are the main driver of BSA changes over time.