Why is BSA used for medication dosing?

Because metabolic rate, blood volume, and organ size all scale more closely with BSA than with body weight alone. Dosing chemotherapy in mg per square metre produces much more consistent drug exposure across very different body sizes than dosing in mg per kilo, which can dangerously overdose obese patients and underdose children.

What's the 'standard' adult BSA of 1.73 m²?

An old reference value still used in renal function reporting (eGFR per 1.73 m2) — derived from a 25-year-old man, 175 cm tall, 73 kg. Your actual BSA may be larger or smaller; eGFR is normalized to 1.73 m2 specifically so values are comparable across very different body sizes. It's a clinical convenience, not a target.

Does BSA change with weight loss?

Yes — significantly. Losing 10 kg reduces BSA by 5 to 7 percent in most adults. For chemotherapy patients this matters enormously and BSA is recalculated every cycle to reflect the patient's actual body size. Under-dosed chemo can let the cancer slip; over-dosed chemo causes severe toxicity. The pharmacist tracks this, but family members are right to keep half an eye on it.

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Body Surface Area (BSA) Calculator

Health

Compute Body Surface Area in m² using 5 published formulas (Mosteller, Du Bois, Haycock, Boyd, Gehan-George) — used in chemotherapy dosing and cardiac index.

Health

Body Surface Area (BSA) Calculator

Generated on May 23, 2026

Weight

Height

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Body Surface Area

BSA 1.849 m² (avg of 5 formulas)

Generated

5/23/2026

Body Surface Area (average of 5 formulas)

1.849 m²

Formula comparison

Du Bois (1916)1.848 m²

Mosteller (1987)1.845 m²

Haycock (1978)1.847 m²

Boyd (1935)1.851 m²

Gehan & George (1970)1.854 m²

Body silhouette (scaled)

Weight

70 kg

Height

175 cm

vs 1.73 m²

107%

Step-by-step calculation

Formula

Mosteller: BSA = √((w × h) / 3600). Du Bois: BSA = 0.007184 × w^0.425 × h^0.725. (w in kg, h in cm.)

1Weight: 70.00 kg, height: 175.0 cm.
2Mosteller (most-used in clinical practice): √(70.00 × 175.0 / 3600) = 1.8447 m².
3Du Bois (oldest, 1916, used in cardiology): 1.8481 m².
4Average across all 5 formulas: 1.8488 m².
5BSA is widely used to dose chemotherapy, calculate cardiac index, and normalize physiological measurements across body sizes.

Clinical use: Body Surface Area is the standard for chemotherapy dosing (mg/m²), cardiac index (L/min/m²), and renal function normalization (eGFR/1.73 m²). Mosteller is the most-used formula in modern clinical practice — simple to compute, accurate within ±5% of the others. For accurate medical dosing, always defer to your physician's preferred formula.

Quick Answer

Compute Body Surface Area in m² using 5 published formulas (Mosteller, Du Bois, Haycock, Boyd, Gehan-George) — used in chemotherapy dosing and cardiac index.

Overview — Body Surface Area (BSA) Calculator

Health

Formula

Mosteller: BSA = √((weight_kg × height_cm) / 3600). Du Bois: 0.007184 × W^0.425 × H^0.725. Average of all 5 typically within 5%.

By Muhammad Salman SaleemUpdated: May 23, 2026MethodologyFree, no sign-upRuns in your browser — your data stays private

From the editors — what to know before you start

Most people end up here because an oncologist mentioned 'BSA' and the family is suddenly trying to understand a number they've never had to think about. Body Surface Area is the square metres of your skin — and it's the unit used to dose chemotherapy (in mg per square metre), normalize cardiac output, and report kidney function. The reason doctors use BSA instead of plain body weight is that metabolic rate, blood volume, and organ size all scale more closely with surface area than with mass alone — which means BSA-based dosing produces more consistent drug exposure across very different bodies than weight-based dosing would. This calculator runs five published formulas at once — Mosteller (the modern default, simple and accurate), Du Bois (1916, still used in cardiology), Haycock (preferred for children), Boyd, and Gehan-George (originally derived for chemotherapy). All five agree within about 5 percent for typical adult sizes. For chemo patients specifically, BSA gets recalculated every cycle because losing or gaining 10 kg shifts the number by 5 to 7 percent — and under-dosed chemo can let the cancer slip while over-dosed chemo causes severe toxicity. If you're tracking BSA because of a family member's cancer treatment, you're not doing the math wrong by checking — you're being a careful family member. Just always defer to the actual oncologist's number; their pharmacist will have already done the calculation for the prescribed regimen, and there are subtle clinical adjustments (capped BSA for very large patients, ideal body weight for very obese patients) that automated calculators don't always handle.

Pro tips most people learn the hard way

Mosteller is the modern clinical default — simple, accurate, and recommended by most pharmacology references for chemotherapy dosing. Du Bois is still standard in cardiology. Haycock is preferred for paediatrics. For everyday tracking, the differences between formulas are clinically insignificant — pick one and stay consistent.
BSA is used for chemotherapy dosing because metabolic rate, blood volume, and organ size scale more closely with body surface area than with weight. Dosing in mg per square metre produces more consistent drug exposure than mg per kilo, which can dangerously overdose obese patients and underdose children.
The 'standard' adult BSA of 1.73 square metres comes from a 25-year-old man at 175 cm and 73 kg. Your actual BSA may be larger or smaller — eGFR (kidney function) is reported per 1.73 to make values comparable across body sizes, which is why your number comes back 'per 1.73 m2'.
BSA changes meaningfully with weight loss — losing 10 kg drops BSA by 5 to 7 percent. For chemotherapy patients specifically, BSA is recalculated every cycle because under-dosed chemo can fail and over-dosed chemo causes severe toxicity. If you're a patient, your pharmacist tracks this. If you're a family member, check the math but defer to the oncologist.
If you're calculating BSA for any reason connected to a serious medical condition — cancer, heart failure, kidney disease — always confirm the number with the treating physician before acting on it. There are clinical adjustments (BSA capping for very large patients, ideal body weight for severe obesity) that home calculators don't always handle.

?What is the Body Surface Area (BSA) Calculator?

The Body Surface Area (BSA) Calculator computes the surface area of the human body in square metres — the standard unit for normalizing physiological measurements across body sizes. BSA is the basis for chemotherapy dosing (mg/m²), cardiac index (cardiac output / BSA in L/min/m²), and renal function reporting (eGFR/1.73 m²). Five published formulas are computed simultaneously and averaged: Mosteller (1987 — most-used clinically), Du Bois (1916 — oldest, cardiology), Haycock (1978 — pediatrics), Boyd (1935), and Gehan-George (1970 — chemotherapy origin). All five agree within 5% for typical adult body sizes.

The Formula

Mosteller: BSA = √((weight_kg × height_cm) / 3600). Du Bois: 0.007184 × W^0.425 × H^0.725. Average of all 5 typically within 5%.

Practical Examples

70 kg, 175 cm: Mosteller gives 1.84 m² (the standard BSA value used in clinical references).

Average adult woman (60 kg, 165 cm): ~1.65 m².

Average adult man (75 kg, 180 cm): ~1.94 m².

Chemotherapy dose for cyclophosphamide: 600 mg/m² → 1,104 mg for a 1.84 m² patient.

Cardiac index in healthy adults: 2.5-4.0 L/min/m² (cardiac output ÷ BSA).

Frequently Asked Questions

Mosteller is the modern clinical default — simple, accurate, and recommended by most pharmacology references for chemotherapy dosing. Du Bois is still common in cardiology departments. Haycock is preferred for paediatrics. For most purposes the differences between formulas are clinically insignificant — pick one and stay consistent across measurements.

Popular Conversions

Jump to a ready-made conversion — useful for quick reference and sharing:

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TDEE Calculator

Compute Total Daily Energy Expenditure from BMR and activity multiplier (sedentary to extra active) to set kcal targets for cutting, maintenance, or bulking.

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Premium Converters

Body Surface Area (BSA) Calculator

Health

Compute Body Surface Area in m² using 5 published formulas (Mosteller, Du Bois, Haycock, Boyd, Gehan-George) — used in chemotherapy dosing and cardiac index.

Health

Body Surface Area (BSA) Calculator

Generated on May 23, 2026

Weight

Height

Save / share— download or share to WhatsApp, Facebook & more

Premium Converters

Body Surface Area

BSA 1.849 m² (avg of 5 formulas)

Generated

5/23/2026

Body Surface Area (average of 5 formulas)

1.849 m²

Formula comparison

Du Bois (1916)1.848 m²

Mosteller (1987)1.845 m²

Haycock (1978)1.847 m²

Boyd (1935)1.851 m²

Gehan & George (1970)1.854 m²

Body silhouette (scaled)

Weight

70 kg

Height

175 cm

vs 1.73 m²

107%

Step-by-step calculation

Formula

Mosteller: BSA = √((w × h) / 3600). Du Bois: BSA = 0.007184 × w^0.425 × h^0.725. (w in kg, h in cm.)

1Weight: 70.00 kg, height: 175.0 cm.
2Mosteller (most-used in clinical practice): √(70.00 × 175.0 / 3600) = 1.8447 m².
3Du Bois (oldest, 1916, used in cardiology): 1.8481 m².
4Average across all 5 formulas: 1.8488 m².
5BSA is widely used to dose chemotherapy, calculate cardiac index, and normalize physiological measurements across body sizes.

Quick Answer

Compute Body Surface Area in m² using 5 published formulas (Mosteller, Du Bois, Haycock, Boyd, Gehan-George) — used in chemotherapy dosing and cardiac index.

Overview — Body Surface Area (BSA) Calculator

Health

Formula

Mosteller: BSA = √((weight_kg × height_cm) / 3600). Du Bois: 0.007184 × W^0.425 × H^0.725. Average of all 5 typically within 5%.

By Muhammad Salman SaleemUpdated: May 23, 2026MethodologyFree, no sign-upRuns in your browser — your data stays private

From the editors — what to know before you start

Pro tips most people learn the hard way

Mosteller is the modern clinical default — simple, accurate, and recommended by most pharmacology references for chemotherapy dosing. Du Bois is still standard in cardiology. Haycock is preferred for paediatrics. For everyday tracking, the differences between formulas are clinically insignificant — pick one and stay consistent.
BSA is used for chemotherapy dosing because metabolic rate, blood volume, and organ size scale more closely with body surface area than with weight. Dosing in mg per square metre produces more consistent drug exposure than mg per kilo, which can dangerously overdose obese patients and underdose children.
The 'standard' adult BSA of 1.73 square metres comes from a 25-year-old man at 175 cm and 73 kg. Your actual BSA may be larger or smaller — eGFR (kidney function) is reported per 1.73 to make values comparable across body sizes, which is why your number comes back 'per 1.73 m2'.
BSA changes meaningfully with weight loss — losing 10 kg drops BSA by 5 to 7 percent. For chemotherapy patients specifically, BSA is recalculated every cycle because under-dosed chemo can fail and over-dosed chemo causes severe toxicity. If you're a patient, your pharmacist tracks this. If you're a family member, check the math but defer to the oncologist.
If you're calculating BSA for any reason connected to a serious medical condition — cancer, heart failure, kidney disease — always confirm the number with the treating physician before acting on it. There are clinical adjustments (BSA capping for very large patients, ideal body weight for severe obesity) that home calculators don't always handle.

?What is the Body Surface Area (BSA) Calculator?

The Formula

Mosteller: BSA = √((weight_kg × height_cm) / 3600). Du Bois: 0.007184 × W^0.425 × H^0.725. Average of all 5 typically within 5%.

Practical Examples

70 kg, 175 cm: Mosteller gives 1.84 m² (the standard BSA value used in clinical references).

Average adult woman (60 kg, 165 cm): ~1.65 m².

Average adult man (75 kg, 180 cm): ~1.94 m².

Chemotherapy dose for cyclophosphamide: 600 mg/m² → 1,104 mg for a 1.84 m² patient.

Cardiac index in healthy adults: 2.5-4.0 L/min/m² (cardiac output ÷ BSA).

Frequently Asked Questions

Popular Conversions

Jump to a ready-made conversion — useful for quick reference and sharing:

Browse all Health

BMI Calculator

Calculate Body Mass Index against WHO and Asian-population thresholds for men and women using kg or lb, cm or inches, with healthy-range guidance.

BMR Calculator

Estimate Basal Metabolic Rate using the Mifflin-St Jeor equation by sex, age, weight and height — the resting kcal/day baseline for diet planning.

TDEE Calculator

Compute Total Daily Energy Expenditure from BMR and activity multiplier (sedentary to extra active) to set kcal targets for cutting, maintenance, or bulking.

Ideal Weight Calculator

Find your ideal weight range in kg and lb using the Robinson, Miller, Devine and Hamwi formulas alongside the BMI 18.5-24.9 healthy band for men and women.

Water Intake Calculator

Calculate daily water intake in millilitres or litres from body weight and exercise minutes, with hot-climate, pregnancy and breastfeeding adjustments.

Body Fat Calculator

Estimate body fat percentage with the US Navy tape-measure method using neck, waist and hip in cm or inches — a no-cost alternative to DEXA scans for men and women.

Macro Calculator

Calculate your daily protein, carbohydrate, and fat targets based on your goals.

Pregnancy Due Date Calculator

Estimate baby's due date using Naegele's rule (LMP + 280 days), adjusted for cycle length, with conception date, trimester boundaries and current week and day.

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See every tool in this category, plus FAQs and category-specific guides.

Browse other categories

Islamic9 Financial14 Gold & Silver8 Unit19 Date & Time9 Math21 Construction22 Utility20 Fun12

Body Surface Area (BSA) Calculator — Body Surface Area in m² using 5 published formulas… | Premium Converters

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Body Surface Area (BSA) Calculator

Body Surface Area (BSA) Calculator

Body Surface Area

Step-by-step calculation

Overview — Body Surface Area (BSA) Calculator

From the editors — what to know before you start

Pro tips most people learn the hard way

?What is the Body Surface Area (BSA) Calculator?

The Formula

Practical Examples

Frequently Asked Questions

Popular Conversions

Embed this calculator on your site

Browse other categories

Premium Converters

Body Surface Area (BSA) Calculator

Body Surface Area (BSA) Calculator

Body Surface Area

Step-by-step calculation

Overview — Body Surface Area (BSA) Calculator

From the editors — what to know before you start

Pro tips most people learn the hard way

?What is the Body Surface Area (BSA) Calculator?

The Formula

Practical Examples

Frequently Asked Questions

Popular Conversions

Embed this calculator on your site

Browse other categories

Premium Converters

Premium Converters

Body Surface Area (BSA) Calculator

Body Surface Area (BSA) Calculator

Step-by-step calculation

Overview — Body Surface Area (BSA) Calculator

From the editors — what to know before you start

Pro tips most people learn the hard way

?What is the Body Surface Area (BSA) Calculator?

The Formula

Practical Examples

Frequently Asked Questions

Which formula should I use?

Why is BSA used for medication dosing?

What's the 'standard' adult BSA of 1.73 m²?

Does BSA change with weight loss?

Popular Conversions

Embed this calculator on your site

More Health Tools

Browse other categories

Premium Converters

Body Surface Area (BSA) Calculator

Body Surface Area (BSA) Calculator

Step-by-step calculation

Overview — Body Surface Area (BSA) Calculator

From the editors — what to know before you start

Pro tips most people learn the hard way

?What is the Body Surface Area (BSA) Calculator?

The Formula

Practical Examples

Frequently Asked Questions

Which formula should I use?

Why is BSA used for medication dosing?

What's the 'standard' adult BSA of 1.73 m²?

Does BSA change with weight loss?

Popular Conversions

Embed this calculator on your site

More Health Tools

Browse other categories