Body Surface Area Calculator - BSA & Army Body Fat Method
You're 170 lb and 5'9", and a clinician needs body surface area for dosing or charting. Mosteller gives about 1.9 m²; DuBois is close but not identical. Enter height and weight below for both BSA formulas, or switch to Army tape mode if you're tracking body fat percentage.
Methodology and limitations
Last reviewed:
Methodology
BSA mode uses DuBois & DuBois (1916) and Mosteller (1987) formulas. Army body fat mode uses US Army circumference method with logarithmic formulas from AR 600-9 and DoDI 1308.3.
Limitations
BSA formulas are clinical estimates for dosing and are not diagnostic. Army body fat method depends on correct tape placement and may be less accurate than DEXA or hydrostatic methods.
Official sources
How BSA and Army Body Fat Are Calculated
You're 170 lb and 5'9", and a clinician needs body surface area for dosing or charting. Mosteller gives about 1.9 m²; DuBois is close but not identical. Enter height and weight below for both BSA formulas, or switch to Army tape mode if you're tracking body fat percentage.
Method used
BSA mode calculates body surface area using DuBois & DuBois (1916) and Mosteller (1987) formulas for medical dosing. Army body fat mode uses US Army circumference method with AR 600-9 standards.
DuBois: BSA = 0.007184 × weight^0.425 × height^0.725; Mosteller: BSA = sqrt((height × weight) / 3600); Army BF: logarithmic formulas by sex from circumferences
Practical example
A 175 lb, 70-inch tall person has a BSA of approximately 1.95 m² (Mosteller). A male with 70" height, 15" neck, 34" waist has ~18% body fat by Army method.
- BSA mode: weight and height
- Army body fat mode: height, neck, waist, hip (females), age
BSA mode shows DuBois, Mosteller, and average BSA. Army mode shows body fat %, category, AR 600-9 standard, and meets-standard flag.
Assumptions
- BSA formulas are clinical estimates for dosing.
- Army method uses correct tape placement.
- Standards vary by age and sex per AR 600-9.
What this includes
- Two BSA formulas with average, Army body fat with standards, age-adjusted criteria, imperial and metric units.
What this excludes
- DEXA or hydrostatic body fat, athlete body composition, burn severity TBSA, pediatric BSA adjustments, clinical diagnosis.
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Frequently Asked Questions
What is body surface area (BSA) used for?
BSA is used in medical settings to help calculate some drug dosages, assess burn surface involvement, and index cardiac output. It relates body size to metabolic rate better than weight alone for certain calculations. This page shows educational DuBois and Mosteller outputs from height and weight. Actual dosing decisions belong exclusively to licensed clinicians—not online calculators.
Which BSA formula is more accurate?
Both DuBois and Mosteller are widely cited; Mosteller is algebraically simpler and often preferred at the bedside. Different specialties may standardize on one equation for consistency. This calculator shows both so you can compare. Small differences are expected and do not replace institutional protocols or pharmacist verification for medication dosing.
How does the US Army body fat method work?
The Army circumference method uses tape measurements and height in logarithmic formulas under fitness regulations such as AR 600-9. Males use neck and waist; females add hip. Results estimate body fat percentage for standard comparisons, not a full clinical body composition workup. Measure carefully and treat outputs as screening estimates alongside official guidance.
How do I measure my waist for Army body fat?
Males typically measure waist at navel level after a normal exhale. Females measure at the narrowest point of the waist. Keep the tape parallel to the floor, snug but not compressing skin, and repeat for consistency. Poor tape placement is a common source of error. Official military measurements follow service-specific instructions beyond this educational tool.
Are Army body fat standards the same for all ages?
No. AR 600-9 and related DoD guidance allow higher maximum body fat percentages for older age brackets. Published male and female limits step upward with age. Confirm the standard that applies to your component and date of regulation, because policy updates occur. This calculator’s educational display is not an official readiness determination.