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Body Fat Calculator

Calculate body fat percentage using the U.S. Navy method or Jackson-Pollock 3-site skinfold method.

Body fat
23.5%
Acceptable
Body fat
23.5%
Acceptable

  • 100% private

    All math runs in your browser. Nothing leaves your device.

  • Formula-verified

    Each calculator is unit-tested against authoritative sources.

  • Instant results

    Static-rendered pages. Sub-second loads on any device.

  • Works offline

    Visit once and it keeps working without an internet connection.

How to use the Body Fat Calculator

  1. 1

    Enter your inputs

    Fill in the required fields at the top of the body fat calculator. Each input shows a default placeholder so you can see the expected format and units before you type.

  2. 2

    Adjust assumptions and options

    Use the toggles, sliders and dropdowns to tailor the calculation to your situation — currency, country, time period, advanced options and any optional fields all change the result in real time.

  3. 3

    Review the result

    The result card updates instantly as you type. Read the headline number, then check the breakdown, chart and any per-period schedule to understand how the inputs combined to produce the answer.

  4. 4

    Compare scenarios

    Change one input at a time to see how sensitive the result is to that variable. This is how you build intuition: small changes that move the answer a lot are the levers that matter.

  5. 5

    Share or save your result

    Copy the shareable link to send the exact scenario to someone else, or use your browser to print or save the page. The URL preserves every input so the recipient sees the same answer you do.

Frequently Asked Questions

  • Men: 10-20% healthy, 6-13% athletic. Women: 18-28% healthy, 14-20% athletic. Below 5% (men) or 13% (women) is essential fat — going lower is unsafe.

  • Navy method has ±3-4% accuracy vs DEXA — sufficient for tracking changes. It's less accurate at extremes (very lean or obese individuals).

  • Men: neck (around larynx) and abdomen at navel. Women: also include hip at widest point. Stand relaxed, measure with tape parallel to floor, no compression.

  • Trained tester with quality calipers: ±3%. Self-measurement: ±5-7%. Consistency matters more than absolute accuracy for tracking trends.

  • Body fat % is more meaningful for athletes and lean individuals. BMI is faster but doesn't distinguish muscle from fat. For most people, both together give the best picture.

  • Realistic rate: 0.5-1% body fat per month with a moderate deficit. Faster losses sacrifice muscle. Track over weeks, not days.

  • The minimum body fat required for normal physiological function — ~3-5% in men, ~12-15% in women (women need more for hormonal/reproductive health).

  • Hydration, food in your gut, time of day and measurement technique all affect numbers. Measure first thing morning, fasted, after using the bathroom, for consistency.

  • Convenient but variable (±5-8% accuracy). Hydration affects readings significantly. Use them for trends only, not absolute numbers.

  • Fat around organs in the abdominal cavity. More dangerous than subcutaneous fat. Waist circumference is a better proxy than total body fat % for visceral risk.

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