Monday, July 6, 2026
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Oncology & Clinical Trial Dosing Calculator

BMI & BSA Calculator — DuBois, Mosteller, Haycock

Calculate Body Mass Index and Body Surface Area using DuBois, Mosteller, and Haycock formulas plus Devine IBW. Built for oncology chemotherapy dosing, Phase 1 dose tables, and clinical weight assessments.

Quick Answer

Body Mass Index (BMI) = weight (kg) ÷ height (m)². Body Surface Area (BSA) for oncology dosing uses DuBois (0.007184 × H^0.725 × W^0.425), Mosteller (√(H×W/3600)), or Haycock for pediatrics — all in m². Ideal Body Weight (Devine) supports lean-mass drugs in obese patients. Many protocols cap BSA at 2.0 m²; confirm institution policy before chemotherapy or trial dose tables.

Key Formulas
BMI = Weightkg / Heightm²
BSA(DuBois) = 0.007184 × H0.725 × W0.425
BSA(Mosteller) = √(H × W / 3600)
BSA(Haycock) = 0.024265 × H0.3964 × W0.5378
H = height in cm    W = weight in kg    BSA in m²

Enter Patient Measurements

Enter weight and height — BMI, BSA, and IBW calculate automatically as you type.

Body measurements
BMI
—
kg/m²
Body Surface Area (BSA)
DuBois Primary
—
m²
Mosteller
—
m²
Haycock Pediatric
—
m²
IBW
—
kg
Oncology Dosing Note: BSA-based chemotherapy dosing uses DuBois or Mosteller. For capped dosing, confirm the institution's cap policy (typically 2.0 m²).

How to Use

1
Enter weight and select the unit (kg or lbs). The calculator converts automatically.
2
Enter height — toggle between cm and feet+inches using the mode buttons.
3
Results calculate automatically as you type. Select sex to get the correct IBW using the Devine formula.

Worked Example

Example Calculation

Patient: Female, 70 kg, 165 cm

BMI = 70 / (1.65)² = 70 / 2.7225 = 25.7 kg/m² (Overweight)

BSA (DuBois) = 0.007184 × 1650.725 × 700.425 = 1.78 m²

BSA (Mosteller) = √(165 × 70 / 3600) = √3.208 = 1.79 m²

IBW (female) = 45.5 + 2.3 × (65.0 in − 60) = 45.5 + 11.5 = 57.0 kg

Pharma & oncology trial context

Body Mass Index (BMI) is a simple screening tool that relates weight to height squared. While it does not directly measure body fat, it is widely used to classify patients as underweight, normal weight, overweight, or obese — categories that have implications for drug dosing, surgical risk, and eligibility in clinical trials.

Body Surface Area (BSA) is used primarily in oncology for chemotherapy dosing because it correlates more closely with cardiac output, renal clearance, and metabolic rate than weight alone. Phase 1–3 protocols specify mg/m² dose levels; document whether DuBois or Mosteller is mandated and whether a 2.0 m² cap applies.

Ideal Body Weight (IBW) using the Devine formula supports drugs distributed in lean body mass — aminoglycosides, vancomycin, and some cytotoxics. Pair with the Dosage Calculator and Creatinine Clearance Calculator when building renal-adjusted regimen tables.

BMI Category Reference

Underweight: < 18.5 Normal: 18.5 – 24.9 Overweight: 25 – 29.9 Obese Class I: 30 – 34.9 Obese Class II: 35 – 39.9 Obese Class III: ≥ 40

Evidence & sources

Frequently Asked Questions

DuBois is the original and most widely referenced BSA formula (1916) and remains the standard in many clinical guidelines. Mosteller (1987) is simpler to calculate and equally accepted in clinical practice, including oncology dosing. Haycock (1978) was derived specifically for pediatric patients and is preferred when calculating BSA for children. In practice, the differences between formulas are small and rarely clinically significant for average-sized adults.
BSA correlates with cardiac output, glomerular filtration rate, and metabolic rate better than body weight alone. This makes BSA a more reliable predictor of drug clearance across patients of different sizes. Using BSA for chemotherapy dosing reduces inter-patient variability in drug exposure, improving the balance between efficacy and toxicity. The practice was established in the 1950s and remains standard for most cytotoxic chemotherapy regimens.
Many institutions cap BSA at 2.0 m² to avoid potential overdose in very large patients, particularly because BSA-based dosing was validated in patients of average size. However, capping is controversial — some guidelines recommend against it for certain drugs, particularly in obese patients where underdosing may compromise efficacy. Always check your institution's policy and the specific drug's prescribing information.
Multiply total height in inches by 2.54. Convert feet and inches to total inches first: (feet × 12) + inches. For example, 5 feet 7 inches = 67 inches × 2.54 = 170.2 cm. This calculator accepts height in cm or feet+inches and converts automatically.
Ideal Body Weight (IBW) is used for drugs that are primarily distributed in lean body mass rather than adipose tissue — such as aminoglycoside antibiotics, vancomycin, and some chemotherapy agents. Using total body weight for these drugs in obese patients would lead to overdosing. IBW is calculated using the Devine formula, which accounts for sex and height.
Adjusted body weight (AdjBW) or actual body weight may be preferred for obese patients when the drug distributes into adipose tissue or when BSA capping would underdose. Many institutions use IBW for aminoglycosides and actual weight if below IBW. Protocol-specific rules in oncology and critical care trials override generic BSA math.
MDCalc's combined BMI/BSA tool reports Mosteller BSA by default. This calculator shows DuBois, Mosteller, and Haycock side-by-side plus Devine IBW — useful when a protocol specifies DuBois (common in older oncology references) or Haycock for pediatric extrapolation.
WHO adult categories: underweight &lt;18.5 kg/m², normal 18.5–24.9, overweight 25–29.9, obese class I 30–34.9, class II 35–39.9, class III ≥40. BMI is a screening tool; it does not measure body composition directly and may misclassify muscular or elderly patients.
First-in-human and Phase 1 cytotoxic protocols often express starting dose as mg/m² based on prior animal NOAEL and human BSA normalization. BSA from DuBois or Mosteller feeds dose level tables; document which formula the protocol mandates and apply caps per pharmacy manual.
Haycock was validated in pediatric populations and is commonly preferred for children. Adult formulas (DuBois, Mosteller) can mis-estimate BSA in infants and adolescents. Confirm the protocol or institutional standard before using pediatric BSA for dosing or trial enrollment.
Multiply the protocol dose in mg/m² by the patient's BSA in m². Example: 75 mg/m² × 1.78 m² = 133.5 mg per cycle. Round per institutional policy and verify against maximum absolute dose in the prescribing information.
No. Chemotherapy dosing requires protocol authorization, renal/hepatic function checks, drug-specific caps, and pharmacist verification. This tool supports BMI, BSA, and IBW arithmetic only.

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