Body Fat Calculator – Accurate Navy Method, Metric & Imperial

Body Fat Calculator

Global, accurate Navy Method — metric & imperial units, instant body fat %, fat mass, lean mass, and visual category chart.

Calculate your body fat percentage

Metric (kg, cm) Imperial (lb, in)

No sliders. Enter your measurements and select Calculate.

Sex

Used for category ranges.

Age

Optional (for context only)

Weight

Kilograms (kg)

Height

Centimeters (cm)

Neck

Neck circumference (cm)

Waist

Waist circumference (cm) at navel

Enter your measurements, then select Calculate Body Fat.

—

Body fat %

—

What is body fat percentage?

Body fat percentage (BF%) estimates how much of your body is fat versus everything else (muscle, bone, organs, water). It’s a practical way to track body composition changes for health, sport, or wellness goals. Unlike weight or BMI alone, BF% reflects the distribution between fat and lean mass, which helps students, professionals, and athletes assess progress more meaningfully.

Navy method: fast, widely used

The Navy method uses simple tape measurements to estimate BF% via logarithms of circumferences and height. For males, it uses neck and waist; for females, neck, waist, and hip. It’s popular because it’s quick, requires no special equipment, and works with metric or imperial units.

Formulas used

Male: BF% = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. Measurements are in inches; metric entries are converted automatically.

Female: BF% = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. Measurements are in inches; metric entries are converted automatically.

How to measure consistently

Neck:

Measure just below the larynx, tape slightly angled downward to the front.

Waist:

Measure horizontally at the navel, relaxed abdomen, after normal exhale.

Hip (female):

Measure at the widest part of the buttocks, tape parallel to the floor.

Categories and interpretation

Typical adult categories differ by sex. 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%+). Athletes and highly muscular individuals may have lower BF% at the same health status; context matters.

Limitations and next steps

Tape-based estimates can vary with tape tension and placement. For higher precision, consider skinfold calipers, bioelectrical impedance (BIA), air displacement plethysmography, or DEXA scans. Use BF% along with habits (nutrition, activity, sleep) and professional guidance to plan sustainable improvements.

Tip: Track trends, not single days. Take measurements at the same time of day, similar hydration and food status, weekly or biweekly.

How-To: Add this Body Fat Calculator to your website

Copy: Copy this entire single-file HTML.
Paste: Add it to your page or CMS (HTML block or template).
Publish: Save, publish, and open the page.
Test: Check on mobiles, iPads, tablets, laptops, and desktops.
Customize: Edit colors, meta tags, and content to match your brand.

FAQs

HOW TO calculate body fat with the Navy method?

Select your units and sex, enter height and required circumferences (plus hip for females), add weight for fat/lean mass, then select “Calculate Body Fat.”

HOW TO measure neck, waist, and hip correctly?

Neck: just below the larynx; Waist: at the navel; Hip (female): widest buttocks point. Keep the tape level and snug, not tight.

HOW TO switch between metric and imperial?

Use the unit chips at the top. Metric uses kg and cm; Imperial uses lb and inches. Conversions happen automatically for the formulas.

HOW TO read my body fat category?

After calculation, your category appears with a highlight on the doughnut chart. Categories differ for men and women and reflect typical ranges.

HOW TO lower body fat safely?

Use modest calorie deficits, prioritize protein, resistance training, daily activity, and consistent sleep. Seek professional advice for personalized plans.

Search Topic: Body Fat Calculator

```