Body Fat Calculator

Estimate your body fat percentage using the U.S. Navy method.

Your Body Composition

Enter your details and measurements on the left to get a complete analysis of your body composition.

Body Fat Calculator – Estimate Your Body Composition Online

The number on the scale doesn’t tell the whole story. Two people can weigh the same but have very different levels of fat and muscle. Our Body Fat Calculator uses the trusted U.S. Navy method to estimate your body fat percentage, lean mass, and healthy ranges so you can track progress that actually matters.

How to Use the Body Fat Calculator

  1. Choose units: Metric (kg, cm) or Imperial (lbs, in).
  2. Enter basics: Age, sex, height, and weight.
  3. Add tape measurements:
    • Neck: Just below the Adam’s apple, tape level, relaxed posture.
    • Waist: Men—at the navel. Women—at the narrowest point of the waist.
    • Hips (women): Around the widest part of the buttocks.
  4. Calculate: Click the button to get your body fat %, fat mass, and lean mass.
  5. Review insights: See your category and suggested healthy range.

All calculations happen instantly in your browser. No signup, no uploads.

Why Body Fat Percentage Matters More Than Weight

  • Clarity over guesswork: BMI and body weight can’t distinguish fat from muscle.
  • Health insight: Higher body fat—especially around the waist—is linked to increased risk of heart disease and type 2 diabetes.
  • Better goal setting: Target a healthy body fat range instead of an arbitrary scale number.
  • Smart nutrition & training: Knowing your lean body mass helps you dial in protein, calories, and strength work.

How the Calculator Works (U.S. Navy Method)

The Navy method estimates body fat from simple circumference measurements. It’s consistent, practical at home, and a solid way to track trends over time.

Formulas (Imperial units – inches):

Men: %BF = 86.010 × log10(Waist − Neck) − 70.041 × log10(Height) + 36.76

Women: %BF = 163.205 × log10(Waist + Hip − Neck) − 97.684 × log10(Height) − 78.387

Metric input is supported: values are converted internally (1 in = 2.54 cm).

Output includes Body Fat %, Fat Mass (weight × body fat %), and Lean Mass (weight − fat mass).

Healthy Body Fat Ranges (ACE Guidelines)

Category Women Men
Essential Fat 10–13% 2–5%
Athletes 14–20% 6–13%
Fitness 21–24% 14–17%
Acceptable 25–31% 18–24%
Obesity 32%+ 25%+

Ranges vary with age, genetics, and training history. Use these bands as a guide—not a verdict.

Pro Tips for Accurate Results

  • Measure consistently: Same time of day, similar hydration, relaxed posture.
  • Use a flexible tape: Keep it level and snug without compressing skin.
  • Take 2–3 readings: Enter the average to reduce small errors.
  • Track trends: Weekly or biweekly checks reveal real progress better than daily swings.

Frequently Asked Questions

Is this calculator accurate?

For most people, the Navy method is typically within a few percentage points when measurements are taken correctly. It’s excellent for monitoring changes over time.

How is this different from BMI?

BMI compares weight to height; it doesn’t distinguish muscle from fat. Body fat % provides a direct view of body composition.

Can athletes use this?

Yes. Very muscular users may find BMI misleading, while body fat % offers a clearer picture of readiness and weight-class goals.

Is any data stored?

Calculations run in your browser. We don’t require accounts or uploads. Your inputs stay with you.

How do I lower my body fat percentage?

Combine a modest calorie deficit with strength training and adequate protein. Focus on sustainable habits, sleep, and recovery for long-term change.

Final Note

Use the Body Fat Calculator as a practical checkpoint, not a diagnosis. Pair the number with how you feel, how you perform, and your long-term goals. Strong, healthy, and consistent beats perfect every time.