How it works

The Navy method estimates body fat from circumference measurements. Men use height, neck, and waist. Women use height, neck, waist, and hip. Metric values are converted to inches internally.

Measurement guide

• Neck: Measure just below the larynx (Adam’s apple), tape slightly downward at front, snug but not compressing.
• Waist: Horizontal around the narrowest point (or navel level if unclear). Relax abdomen; do not suck in.
• Hips (women): Around the widest part of the buttocks.
• Height: Barefoot, against a wall, normal posture.

Worked examples (male & female)

• Male (metric): 178 cm height, neck 40 cm, waist 86 cm → converts to inches and yields roughly ~18% BF.
• Female (metric): 165 cm height, neck 34 cm, waist 72 cm, hip 98 cm → about ~25% BF.
• Male (imperial): 70 in height, neck 15 in, waist 34 in → about ~18% BF.

US Navy formula notes & limitations

• Field estimate intended for screening; not a medical diagnosis.
• Hydration, tape tension, posture, and site placement affect readings.
• Very muscular neck/upper‑back can read lower BF% versus lab methods.
• Consider confirming with DXA, BIA, Bod Pod, or skilled caliper assessment.

BF% vs BMI vs WHR

• BF%: Estimates fat proportion. Good for physique tracking.
• BMI: Weight relative to height; cannot separate fat from muscle.
• WHR: Fat distribution (waist vs hips) linked to cardio‑metabolic risk.
• Use multiple indicators for a fuller view of health and performance.

Categories (reference ranges)

• Men: Essential 2–5%, Athletes 6–13%, Fitness 14–17%, Average 18–24%, Obese 25%+
• Women: Essential 10–13%, Athletes 14–20%, Fitness 21–24%, Average 25–31%, Obese 32%+

Tips & caveats

• Measure at the same time of day and hydration level for trends.
• Use a flexible, non‑stretch tape and keep it level (parallel to the floor).
• Compare with other indicators: BMI, WHR, strength progress, and photos.
• For medical decisions, consult a clinician or use clinical methods (DXA, BIA, Bod Pod).

How to reduce body fat safely

• Moderate calorie deficit with adequate protein and whole foods.
• Combine resistance training (muscle retention) with cardio.
• Prioritize sleep and stress management; both impact appetite and recovery.
• Track trends every 2–4 weeks; avoid day‑to‑day overreactions.

Common pitfalls

• Pulling the tape too tight or measuring over clothing.
• Changing waist/neck level between sessions or altering posture.
• Comparing Navy estimates one‑to‑one with DXA values.

Educational use only; not a substitute for professional medical advice or diagnosis.