Body Fat Calculator

Estimate body fat percentage using the US Navy circumference method.

Body fat estimates from circumference measurements carry a ±3–5% error margin. For clinical body composition analysis, use DEXA scanning. This tool does not provide medical advice.

Height (cm)

Waist (cm)

Neck (cm)

Hip (cm)

Body Fat Percentage

Reference: Essential (M: 2–5%, W: 10–13%), Athletic (M: 6–13%, W: 14–20%), Average (M: 18–24%, W: 25–31%)

How It Works

Enter your height, waist, neck, and (for women) hip circumference measurements. The calculator estimates your body fat percentage using the US Navy formula.

**Body Fat Calculator — Estimate Your Body Composition**

Body fat percentage is a more informative health metric than total body weight or BMI because it distinguishes between fat mass and lean mass (muscle, bone, organs, water). Our Body Fat Calculator uses the US Navy circumference method — a validated field measurement technique used by the US military.

**US Navy Body Fat Formula**

**Men:**
BF% = 495 / (1.0324 – 0.19077 × log10(waist – neck) + 0.15456 × log10(height)) – 450

**Women:**
BF% = 495 / (1.29579 – 0.35004 × log10(waist + hip – neck) + 0.22100 × log10(height)) – 450

(Measurements in centimetres)

**How to Take Measurements Accurately**

- **Waist:** Measure at the narrowest point (or just above the navel for men, at the navel for the Navy method)
- **Neck:** Measure just below the larynx (Adam's apple), sloping slightly down in front
- **Hips (women only):** Measure at the widest point of the buttocks
- Use a flexible measuring tape, keep it parallel to the floor, and don't suck in your stomach

**Body Fat Percentage Categories (ACSM)**

| Category | Men | Women |
|---|---|---|
| Essential Fat | 2–5% | 10–13% |
| Athletic | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |

**Why Body Fat Percentage Beats BMI**

Two people with the same BMI can have very different health profiles. A 90 kg person with 15% body fat (muscle-dominant) is very different from a 90 kg person with 35% body fat. BMI can't distinguish these cases; body fat percentage can.

**Accuracy Note**

The Navy method has an accuracy of ±3–4%. More precise methods include DEXA scan (gold standard, ±1–2%), hydrostatic weighing, and air displacement plethysmography (Bod Pod). Skinfold callipers are also more accurate but require proper technique.

Frequently Asked Questions

The US Navy method has an accuracy of approximately ±3–4%. DEXA scanning (±1–2%) is the most accurate non-invasive method.

For men, 14–17% (fitness) to 18–24% (average) is healthy. For women, 21–24% (fitness) to 25–31% (average). Athletes typically carry less: 6–13% for men, 14–20% for women.

For the Navy method, men measure at the navel; women at the narrowest point of the waist. Keep the tape parallel to the floor and don't pull it tight.

Caloric deficit combined with resistance training preserves muscle while losing fat, which reduces body fat percentage most effectively. Cardio aids the caloric deficit but can also cause some muscle loss if overdone.

Essential fat (2–5% for men, 10–13% for women) is the minimum fat required for normal physiological functioning, including protecting organs and producing hormones. Going below this is dangerous.