Body Fat Calculator

Free body fat calculator using U.S. Navy and BMI methods. Enter neck, waist, and hip measurements for body fat %, fat mass, lean mass, and fitness category.

Measure just below the Adam's apple.

Measure at the navel.

Body Fat
17.9%
Fitness

U.S. Navy Method

Target
16.0%
1.4 kg fat mass to lose

ACE Fitness range target

Body Fat Breakdown

Detailed breakdown of your body fat metrics and composition

Body Composition
Total: 72 kg
18%
82%
Fat12.9 kg
Lean59.1 kg

Estimates based on population formulas. Navy method uses body measurements and is generally more accurate than BMI-based estimates.

Body Fat Category Table

ACE body fat ranges by category for men (Navy method)

ACE (American Council on Exercise) body fat percentage ranges by category for men (Navy method).

Method Comparison

We estimate body fat using both the Navy and BMI methods.

Navy method
18%

Uses neck, waist, and hip (for women) measurements along with height to estimate body fat.

BMI method
20%

Based on BMI and age. Quick to calculate, but less personalized for muscular or very lean bodies.

For very muscular or very lean individuals, measurement-based methods or professional tools may give better estimates than BMI-based formulas.

Visual Comparison

See where your body fat percentage falls relative to the healthy range. (Navy method)

Healthy Range
Men: 8–19%
18
0
8
19
100
Your Body Fat: 18%
Within healthy range

The healthy range shown is based on ACE (American Council on Exercise) guidelines. Body fat percentage can vary with age, muscle mass, and fitness goals. For athletes or those with high muscle mass, body fat may naturally fall outside these ranges.

What Is Body Fat Percentage?

Essential vs. storage fat and why the ratio matters

Body fat percentage is the share of your total weight made up of fat tissue. Everyone needs some fat for hormone production, organ protection, and healthy cell function — this is called essential fat. Storage fat is the extra reserve your body keeps for later use.

EssentialOrgans & hormones
StorageEnergy reserve
VisceralAround organs
SubcutaneousUnder the skin
Essential fat (men)
2–5%
Essential fat (women)
10–13%

Why body fat % beats BMI

Two people at the same BMI can have very different body compositions. A 30-year-old athlete at BMI 27 may be 15% body fat; a sedentary person at BMI 27 may be 30%. Body fat % is the more meaningful metric for fitness and health risk.

How This Calculator Estimates Body Fat

Navy method and BMI method formulas explained

Navy MethodTape measurements + height
BMI MethodBMI + age formula

Navy method (U.S. DoD circumference method): Uses neck, waist, and (for women) hip measurements plus height. Developed by the U.S. Navy and used across all military branches including the Army (ABCP), Air Force, and Marine Corps.

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

BMI method (Deurenberg equation): Uses BMI and age for a quick estimate. Simple but less personalized for very lean or muscular bodies.

Men

BF% = 1.20 × BMI + 0.23 × age - 16.2

Women

BF% = 1.20 × BMI + 0.23 × age - 5.4

Which method is more accurate?

The Navy method is generally ±3–4% for most people. The BMI method is quicker but can overestimate fat in muscular individuals and underestimate in the elderly.

How to Calculate Body Fat Percentage at Home

Tape measure method step-by-step — no calipers needed

The circumference (tape measure) method is the most practical way to estimate body fat at home. It is the same approach used by the U.S. Navy, Army, and Air Force.

1

Measure your neck

Wrap tape just below the Adam's apple. Keep it level and snug but not tight.

2

Measure your waist

Men: measure at the navel. Women: measure at the narrowest part of your waist.

3

Measure your hips (women only)

Measure at the widest point of the hips and buttocks.

4

Enter height & weight

Height feeds the Navy formula. Weight is used for the BMI comparison method.

5

Read your result

The Navy formula converts these circumference measurements into an estimated body fat %.

Measurement tips

Measure at the same time each day (morning, before eating). Repeat 2–3 times and average. Keep the tape snug but not compressing the skin. Use a flexible cloth tape, not a metal one.

Army & Military Body Fat Standards

ABCP maximum body fat limits by age and gender

The U.S. Army Body Composition Program (ABCP) uses the same circumference-based formula as the Navy method. Soldiers who exceed the screening weight must pass a body fat tape test. This calculator uses that same DoD formula.

Age groupMen (max)Women (max)
17–2020%30%
21–2722%32%
28–3924%34%
40+26%36%

All branches, one formula

The Navy, Air Force, and Marine Corps each have their own maximum body fat thresholds, but all branches use the same tape-measure circumference formula for measurement.

Ideal Body Fat Percentage by Age & Category

ACE healthy ranges for men and women

The American Council on Exercise (ACE) defines five body fat categories. Healthy ranges shift upward with age as muscle mass naturally decreases.

Essential fat

2–5%10–13%

Athletes

6–13%14–20%

Fitness

14–17%21–24%

Average

18–24%25–31%

Obese

25%+32%+

Body Fat Measurement Methods Compared

Tape measure, calipers, DEXA, and more

Tape Measure±3–4% · Free
Calipers±3–5% · $10–30
BIA Scales±4–8% · $30–200
DEXA Scan±1–2% · $50–150
Hydrostatic±1–2% · $50–150
Bod Pod±2–3% · $50–75

Skinfold calipers vs. tape measure

Calipers pinch skin folds at 3–7 sites (chest, abdomen, thigh, tricep, suprailiac) and use thickness measurements in a formula. They can be more precise than tape but require practice to use consistently. The tape method is easier and works well for most people.

How to Reduce Body Fat — Evidence-Based Tips

Sustainable strategies for healthy body composition

Do this

  • Calorie deficit of 300–500 kcal/day
  • Resistance training 3–4× per week
  • Protein 0.7–1 g per lb of bodyweight
  • Sleep 7–9 hours per night
  • Re-measure every 4–8 weeks

Avoid this

  • Crash diets or extreme calorie cuts
  • Cardio only — muscle loss follows
  • Skipping meals or fasting recklessly
  • Targeting below essential fat levels
  • Daily weigh-ins — weekly is enough

Slow

0.25%

per month

Moderate

0.5%

per month

Aggressive

1.0%

per month

Realistic targets

Most people can safely lose 0.5–1% body fat per month. Drastic cuts below essential fat levels disrupt hormones, immunity, and energy. Focus on body composition (muscle vs. fat) rather than the lowest possible number.

Limitations of Online Body Fat Calculators

Why estimates differ from clinical measurements

Tape placement & tension
Main error source
Hydration level
Can shift result ±2%
Muscular individuals
BMI method overestimates
Central obesity
Navy method may underestimate
Age > 65
Formulas less validated

When to get a clinical measurement

If your results are far outside healthy ranges, or you have symptoms like fatigue, hair loss, or irregular cycles, consult a healthcare provider. DEXA scans and hydrostatic weighing are the gold standard for precision.

Healthy Body Fat Ranges & When to See a Doctor

Gender-specific ranges and warning signs

Healthy ranges differ for men and women and shift with age. Very low body fat can disrupt hormones and energy; very high body fat increases risks for heart disease, type 2 diabetes, and joint stress.

Healthy range (men, 20–39)
8–19%
Healthy range (men, 40–59)
11–21%
Healthy range (women, 20–39)
21–32%
Healthy range (women, 40–59)
23–33%

Warning signs

Seek medical advice if body fat is far outside ranges, or you experience unexplained weight changes, fatigue, irregular periods, or difficulty recovering from exercise.

Frequently Asked Questions

Common questions about body fat percentage and measurement methods

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Last updated Mar 18, 2026