SnapCalc

Body Fat Percentage Estimator

Estimate your body fat percentage using the US Navy method based on height, neck, waist, and hip measurements.

Embed

Measure just below the larynx

Males: at navel | Females: narrowest point

Females only — widest point of hips

How to Use This Body Fat Calculator

This calculator uses the US Navy circumference method — a free, accessible alternative to expensive DEXA scans or hydrostatic weighing that’s accurate enough for tracking progress over time.

What You’ll Need

A flexible tape measure and about 2 minutes. Take all measurements in the morning before eating.

  • Height — standing height in cm
  • Neck — circumference just below the larynx (Adam’s apple), tape slightly angled down at the front
  • Waist — males: at the navel | females: at the narrowest point between ribs and hips
  • Hips (females only) — at the widest point of the hips and buttocks
  • Weight — used to calculate your fat mass and lean mass in kilograms

    • Measurement Tips for Accuracy

  • Pull the tape snug but not compressing the skin
  • Take 2–3 measurements and use the average
  • Measure at the same time of day each session — morning is most consistent
  • Stand straight and relaxed, not holding your breath or sucking in

    • Understanding Your Results

  • Body Fat % — the percentage of your total weight that is fat tissue
  • Fat Mass — actual kilograms of body fat
  • Lean Mass — everything else: muscle, bone, organs, water
  • Category — classified against American Council on Exercise (ACE) ranges

    • Body Fat Categories (ACE)

    Men: Essential <6% | Athletic 6–13% | Fit 14–17% | Average 18–24% | Obese 25%+ Women: Essential <14% | Athletic 14–20% | Fit 21–24% | Average 25–31% | Obese 32%+

    Formula

    US Navy Method — Male: 495/(1.0324 − 0.19077×log(waist−neck) + 0.15456×log(height)) − 450

    Frequently Asked Questions

    How accurate is the US Navy body fat method?

    The US Navy method has a margin of error of ±3–4% compared to DEXA scans. It’s less accurate than hydrostatic weighing or DEXA, but far more accessible and consistent enough for tracking trends over weeks and months.

    What is a healthy body fat percentage?

    For men, 10–20% is the fit-to-average range. For women, 18–28%. Athletes are often lower. Essential fat (minimum for survival and hormonal function) is ~3% for men and ~12% for women — going below these levels is medically dangerous.

    Why does my waist need to be larger than my neck?

    The US Navy formula uses the difference between waist and neck measurements in a logarithm. If the neck is equal to or larger than the waist, the calculation produces an invalid result. This reflects an extreme (and unhealthy) body composition.

    How often should I measure my body fat?

    Monthly is ideal. Body fat changes slowly — weekly measurements pick up normal fluctuations from water retention, digestion, and measuring technique rather than real fat loss. Monthly gives a cleaner signal.

    Is body fat percentage more useful than BMI?

    Yes, for most purposes. BMI doesn’t distinguish between muscle and fat — a muscular athlete and an overweight person can have the same BMI. Body fat percentage directly measures composition, making it a more actionable health metric.

    Embed on your website

    Free. Works everywhere. Always up to date. Your readers get the tool — you keep the page.

    Paste this snippet anywhere in your HTML.

    <iframe src="https://snapcalc.tools/embed/body-fat-calculator" width="100%" height="520" frameborder="0" scrolling="no" title="Body Fat Percentage Estimator" ></iframe>

    Related Calculators

    monitor_heart

    Calorie & Macros (TDEE)

    Calculate your Total Daily Energy Expenditure (TDEE), ideal calorie intake, and macronutrient targets for your goal.

    Open Toolarrow_forward
    monitor_heart

    Daily Water Intake

    Calculate how much water you should drink per day based on your weight, activity level, and climate.

    Open Toolarrow_forward
    monitor_heart

    Running Pace & Race Time Predictor

    Calculate your running pace, finish time, or required distance. Predict race times for 5K, 10K, half marathon, and marathon.

    Open Toolarrow_forward