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Body Fat Calculator

Calculate body fat percentage using the US Navy formula.

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Unit
Formula

Why body fat % matters more than body weight

Two people can weigh the same yet have very different body compositions. A person with 15% body fat and 85% lean mass is metabolically healthier than someone with 30% body fat at the same weight. Body fat percentage gives a more accurate picture of health risk, fitness level, and the effectiveness of diet and exercise programmes.

US Navy method vs BMI method

The US Navy formula requires circumference measurements and is more accurate for most people. The BMI-based Deurenberg formula needs only weight, height, age, and sex — it is less accurate but useful when you cannot take body measurements. Use the Navy method whenever possible.

How to reduce body fat healthily

  • Maintain a moderate calorie deficit (300–500 kcal/day) — extreme restriction loses muscle mass too.
  • Prioritise protein (1.6–2.2 g/kg of body weight) to preserve lean mass during a cut.
  • Include resistance training 3–4 days per week to maintain or build muscle while losing fat.
  • Aim for 0.5–1% of body weight loss per week — faster rates sacrifice lean mass.

Frequently asked questions

How is body fat percentage calculated?
This calculator offers two methods. The US Navy formula uses circumference measurements (waist, neck, and hip for women) along with height to estimate body fat using a logarithmic formula. The BMI-based Deurenberg formula uses BMI, age, and sex. Both are estimates — the gold standard is DEXA scan.
What is a healthy body fat percentage?
For men: 6–13% (athletes), 14–17% (fitness), 18–24% (acceptable). For women: 14–20% (athletes), 21–24% (fitness), 25–31% (acceptable). Below essential fat levels (men <5%, women <10%) is dangerous. Above obese thresholds (men >25%, women >32%) increases health risks.
How do I measure my waist accurately?
For the US Navy formula, measure your waist at the navel level while exhaling normally. Do not suck in or push out. Measure neck at the narrowest point, just below the Adam's apple. Women measure hips at the widest point across the buttocks.
How accurate is the US Navy formula?
The US Navy method has a margin of error of about ±3–4% compared to hydrostatic weighing. It is considered reasonably accurate for most people and is widely used by the military and fitness professionals. It may be less accurate for very muscular individuals or those with unusual body proportions.
What is lean body mass?
Lean body mass (LBM) is everything in your body except fat — muscles, bones, organs, water, and connective tissue. It is calculated as: LBM = Total Weight × (1 − body fat%). Increasing LBM through strength training raises your metabolic rate and improves body composition even without losing weight.

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