Calculator Comparison

Body Fat Calculator vs Body Surface Area Calculator

Not sure which calculator to use? Here's a side-by-side comparison of the Body Fat Calculator and Body Surface Area Calculator to help you pick the right one for your needs.

Body Fat Calculator

Health & Fitness

Estimate your body fat percentage using body measurements with the U.S. Navy method for men and women.

What you enter

Gender
Weight (lbs)
Waist (inches)
Neck (inches)
Height (inches)

What you get

Body Fat Percentage(primary)
Fat Mass
Lean Body Mass
Body Fat Category

Use Body Fat Calculator

Body Surface Area Calculator

Health & Fitness

Calculate your body surface area (BSA) using multiple validated formulas including Mosteller and Du Bois methods.

What you enter

Weight (lbs)
Height (feet)
Height (inches)
Formula

What you get

Body Surface Area (m²)(primary)
Body Surface Area (ft²)
Formula Used

Use Body Surface Area Calculator

Key Differences

Feature	Body Fat Calculator	Body Surface Area Calculator
Category	Health & Fitness	Health & Fitness
Inputs	5 required fields	4 required fields
Outputs	4 results	3 results
Chart	No chart	No chart
FAQs	6 answered	3 answered

Input Comparison

Shared Inputs

Weight (lbs)
Height (inches)

Only in Body Fat Calculator

Gender
Waist (inches)
Neck (inches)
Hip (inches, women only)

Only in Body Surface Area Calculator

Height (feet)
Formula

Which Calculator Should You Use?

Use the Body Fat Calculator if you need to:

Calculate body fat percentage
When you know your gender and weight (lbs)

Use the Body Surface Area Calculator if you need to:

Calculate body surface area (m²)
When you know your weight (lbs) and height (feet)

Frequently Asked Questions

What is a healthy body fat percentage?

For men, essential fat is 2–5%, athletic range is 6–13%, fitness range is 14–17%, and average is 18–24%. For women, essential fat is 10–13%, athletic is 14–20%, fitness is 21–24%, and average is 25–31%. Above 25% (men) or 32% (women) is generally considered obese.

How accurate is the Navy method?

The U.S. Navy body fat formula uses neck, waist, and hip measurements to estimate body fat. Studies show it's accurate within 3–4 percentage points for most people — sufficient for tracking trends. It's less accurate for very muscular individuals and those with unusual fat distribution patterns.

What is body surface area used for?

BSA is primarily used in medicine to calculate drug dosages, especially chemotherapy. It also helps determine cardiac index, renal function, and burn severity assessment.

Which BSA formula is most accurate?

The Mosteller formula is most widely used due to its simplicity and accuracy. The Du Bois formula is the original standard. Both provide clinically equivalent results for most adults.

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Bottom Line

Choose the Body Fat Calculator if you need to calculate body fat percentage. Use the Body Surface Area Calculator if you need to calculate body surface area (m²). Both calculators are free and require no sign-up.

Use Body Fat Calculator Use Body Surface Area Calculator

Feature

Body Fat Calculator

Body Surface Area Calculator