Body Fat Calculator
Calculate body fat percentage using the US Navy tape measure method
tuneBody Measurements
Gender
Height (cm)
cm
Body Weight (kg) (for fat/lean mass)
kg
Waist Circumference (cm)
cm
Neck Circumference (cm)
cm
US Navy Formula
Male: BF% = 86.01×log₁₀(waist−neck) − 70.041×log₁₀(height) + 36.76
Female: BF% = 163.205×log₁₀(waist+hip−neck) − 97.684×log₁₀(height) − 78.387
Body Fat %
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Body Fat %
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Category
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Fat Mass
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Lean Mass
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Body Fat Category Reference
| Category | Men (%) | Women (%) |
|---|---|---|
| Essential Fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | ≥25% | ≥32% |
What is a Body Fat Calculator?
Body fat percentage is the proportion of fat mass in your total body weight. Unlike BMI, it distinguishes between fat and lean mass (muscle, bone, organs), making it a more accurate indicator of fitness and health. Essential fat for men is 2–5%, for women 10–13%.
The US Navy Method used in this calculator requires only waist, neck, and height measurements (plus hip for women). It's a practical field method accurate to within 1–3% of lab-based measurements, making it ideal for tracking fitness progress over time.
lightbulb Example Calculation
Scenario: Mr. Vikram Singh, 25-year-old gym enthusiast in Mumbai — height 183 cm (6'0"), waist 88 cm (34.6"), neck 40 cm (15.7"), wants to know his body fat % before a bodybuilding competition prep
1Navy formula (male): BF% = 495 / (1.0324 − 0.19077×log(88−40) + 0.15456×log(183)) − 450
2BF% = 495 / (1.0324 − 0.19077×1.681 + 0.15456×2.262) − 450 ≈ 18.5%
3At 18.5% with 80 kg body weight: Fat mass ≈ 14.8 kg | Lean mass ≈ 65.2 kg
✓ Result: Vikram's body fat is ~18.5% — "Fitness" category. Targeting 10–12% for competition requires losing ~5–6 kg of fat.
help_outlineHow to Use the Body Fat Calculator
- Select your gender — the US Navy formula differs for males (uses waist and neck) and females (adds hip measurement).
- Enter your height in centimetres and your body weight in kilograms — weight is used to calculate fat mass and lean mass in kilograms.
- Measure and enter your waist circumference at the narrowest point — for men this is typically around the navel level; stand relaxed and measure after exhaling.
- Measure and enter your neck circumference just below the Adam's apple. For women, also measure and enter hip circumference at the widest point around the buttocks.
- Click Calculate Body Fat to see your body fat percentage, category (Essential / Athlete / Fitness / Average / Obese), fat mass in kg, and lean mass in kg.
Benefits
- More meaningful than BMI — distinguishes fat from muscle mass
- Only requires a flexible tape measure — no expensive lab equipment needed
- Shows fat mass and lean mass in kilograms for concrete fitness targets
- Retest monthly to track body composition changes during diet or exercise programs
- Category reference table (Essential, Athlete, Fitness, Average, Obese) makes interpretation intuitive
Key Terms
- Body Fat Percentage
- The proportion of total body weight that is fat tissue. Unlike BMI, it accounts for body composition — muscle vs. fat.
- US Navy Method
- A circumference-based formula using waist, neck, and height (plus hip for women) to estimate body fat — accurate to ±1–3% of DEXA scans.
- Fat Mass
- The absolute weight of fat tissue in kilograms = Total body weight × Body fat %.
- Lean Mass
- Total body weight minus fat mass — includes skeletal muscle, bone, organs, and water. The foundation of metabolic health.
- Essential Fat
- The minimum fat needed for physiological functions — approximately 2–5% for men, 10–13% for women. Below this, health risks increase significantly.
quizFrequently Asked Questions
How accurate is the US Navy method compared to DEXA scans?
The US Navy circumference method is accurate within ±1–3% of lab-based methods like DEXA (dual-energy X-ray absorptiometry) for most people with average body compositions. It tends to overestimate body fat in very muscular individuals and underestimate it in those with unusual fat distribution (e.g., abdominal obesity with thin limbs). For tracking trends over time rather than absolute accuracy, the Navy method is excellent and far more practical.
How do I correctly measure waist, neck, and hip?
Waist: Measure at the narrowest point (for men, just above the navel; for women, midway between lowest rib and hip bone). Measure after a normal exhale — do not suck in. Neck: Measure just below the larynx (Adam's apple), keeping the tape horizontal and snug but not tight. Hip (women): Measure at the widest point around the buttocks and hips. Take each measurement 2–3 times and use the average for accuracy.
What is the ideal body fat percentage for fitness?
The "Fitness" category — 14–17% for men and 21–24% for women — represents a healthy, athletic physique without elite athletic leanness. Athletes typically range 6–13% (men) and 14–20% (women). The optimal range depends on your goals: endurance athletes may thrive at 8–10% (men), while recreational fitness enthusiasts are healthy anywhere in the Fitness to low-Average range. Going below essential fat levels (under 5% for men) is dangerous.
Is body fat percentage a better indicator than BMI for health assessment?
Body fat percentage is generally more informative because it directly measures what matters — fat mass vs. lean mass. A muscular person with a BMI of 28 (classified as overweight) may have only 12% body fat and be extremely healthy. Conversely, a "normal" BMI person of 22 may have 30% body fat (called "skinny fat") with metabolic risk. For fitness tracking, body fat % is superior; for quick population-level screening, BMI is simpler and still widely used clinically.
How often should I measure my body fat?
For tracking progress during a fitness program, measuring body fat once every 4–6 weeks is ideal. More frequent measurement introduces noise from day-to-day fluctuations in hydration (which affects lean mass readings). Measure under consistent conditions — same time of day, same hydration state, same tape measure — for comparable results. Keep a log of measurements to see trends over 3–6 months of training or dieting.
Can I lose fat only from specific areas (spot reduction)?
No — spot reduction is a fitness myth. The body draws on fat stores from throughout the body based on genetics, not based on which muscles are exercised locally. Doing 500 crunches will not specifically reduce belly fat. To reduce fat in any area, overall body fat percentage must be lowered through a calorie deficit (diet + cardio). Strength training builds muscle everywhere but does not selectively reduce fat in the trained area.