Your weight on the scale only tells half the story. Two people can weigh exactly 75 kg — one lean and athletic, the other carrying a high amount of body fat — and their health outlook is completely different. Body fat percentage tells you what fraction of your body weight is actually fat tissue versus muscle, bone, and water, and it’s a far better gauge of fitness and metabolic health than weight or even BMI. The gold-standard lab methods (DEXA scans, hydrostatic weighing) cost thousands of rupees and need a clinic visit. Our free body fat calculator uses the US Navy method — a tape-measure formula developed by the United States Navy and validated against lab measurements — so you can get a reliable estimate at home in two minutes.
Body Fat Calculator
What Is the US Navy Method?
In 1984, researchers at the US Naval Health Research Center published circumference-based equations for estimating body fat from simple tape measurements — height, neck, waist (and hips for women). The formulas were derived by comparing tape measurements against underwater weighing in hundreds of subjects, and they remain one of the most practical field methods in fitness and military screening worldwide. The equations use logarithms of the circumferences, which is why the calculator does the maths for you. Studies have found the Navy method typically lands within 3–4% of lab-grade measurements — more than good enough for tracking your own progress.
Male: 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Female: 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
(All measurements in centimetres.)
| Category (Men) | Body fat % | Category (Women) | Body fat % |
|---|---|---|---|
| Essential fat | 2–5% | Essential fat | 10–13% |
| Athletic | 6–13% | Athletic | 14–20% |
| Fit | 14–17% | Fit | 21–24% |
| Average | 18–24% | Average | 25–31% |
| Obese | 25%+ | Obese | 32%+ |
How to Use
- Select your gender — the formula differs for men and women.
- Measure your height in cm (no shoes, standing straight).
- Measure your neck just below the Adam’s apple, tape snug but not tight.
- Measure your waist at the narrowest point (men) or at the navel level — keep the tape level and breathe normally.
- Women also measure hips at the widest point.
- Click Calculate — your body fat percentage and category appear instantly. Re-measure every 2–4 weeks to track change.
Worked Example
Bilal is 175 cm tall, with a 38 cm neck and an 85 cm waist. Waist − neck = 47 cm. Plugging into the male formula: 86.010 × log₁₀(47) − 70.041 × log₁₀(175) + 36.76 = 86.010 × 1.672 − 70.041 × 2.243 + 36.76 ≈ 23.5% — the “Average” category. If he trains and his waist drops to 80 cm while everything else stays the same, his estimate falls to about 20% — visible progress the bathroom scale alone would never show.
Tips & Limitations
- Measure in the morning before eating, and use the same tape positions every time — consistency matters more than perfection.
- Don’t pull the tape tight enough to compress the skin; just snug.
- The Navy method assumes average body proportions — very muscular or very unusual builds can skew it slightly.
- For the most complete picture, combine this with your BMI and waist-to-hip ratio — all three are free on this site.
- Losing 1% of body fat per month is excellent progress; crash dieting usually burns muscle instead.
FAQs
Is the US Navy method accurate?
Within about 3–4 percentage points of lab methods like DEXA for most people — accurate enough to track trends and set goals, though not a medical diagnosis.
What is a healthy body fat percentage?
For men, roughly 14–24% depending on age and goals; for women, roughly 21–31%. Athletes sit lower (men 6–13%, women 14–20%). Below essential-fat levels (under ~5% men, ~10–13% women) is unhealthy.
Why does the formula need my neck measurement?
Neck circumference helps the equation distinguish frame size and lean mass from waist fat — it’s what makes the estimate much better than waist alone.
Body fat percentage vs BMI — which should I trust?
Body fat percentage, when measured reasonably. BMI can misclassify muscular people; body fat % measures what actually matters for metabolic health. Ideally track both.
How fast can I lower my body fat?
A realistic, sustainable rate is about 0.5–1% per month through a modest calorie deficit plus resistance training. Anything dramatically faster usually costs you muscle.