Enter your measurements
Keep the unit system consistent for every field. US Navy requires neck and waist (plus hip for women). BMI (Deurenberg) requires weight.
Results
Enter your measurements and choose a method to estimate body fat percentage.
Please check the highlighted fields and try again.
Body fat percentage
Category
Fat mass
Lean mass
For information only; measurement methods and individual factors vary. Not a medical diagnosis.
Measurement guide
- Neck: tape just below the Adam’s apple while looking forward.
- Waist: tape at the narrowest natural waist or navel line, after a gentle exhale.
- Hip (women): tape at the widest point over the buttocks.
- Consistency: take measurements at the same time of day, in minimal clothing, and average multiple readings.
US Navy and BMI formulas estimate population averages. Muscle mass, body shape, hydration, and ethnicity can shift results.
Interpretation (and an example)
- US Navy (circumference) uses neck/waist (and hip for women). Small tape placement differences can change the estimate.
- BMI-based (Deurenberg) uses height, weight, age, and sex. It can be less accurate for very muscular bodies or atypical fat distribution.
- Fat mass / lean mass are derived from body weight × body fat %, so any weight error carries through.
Mini example
If you weigh 80 kg and your estimate is 20%, fat mass is about 16 kg and lean mass about 64 kg. Use this to track trends over time rather than a single “true” value.
Tips to reduce measurement noise
- Measure at the same time of day, under similar hydration and meal conditions.
- Take 2–3 measurements and average them, especially for waist/hip.
- For health decisions, confirm with a clinician and, if needed, a lab method (DEXA, Bod Pod, hydrostatic weighing).
References
Recent calculations
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How to use this page effectively
This guide helps you use Body Fat Percentage Calculator as a practical decision page: start with the key section, confirm assumptions, and use related links to move from overview to the exact tool or topic you need.
How it works
This page is designed as an orientation layer. It summarizes a topic, highlights the most common decision paths, and links to task-specific tools or deeper references. The best workflow is to read the short context first, choose one concrete objective, and then follow a single linked action path. By avoiding parallel jumps across many links, you reduce context switching and make results easier to reproduce.
When to use
Use this page when you are not yet sure which calculator or resource is the right fit, or when you need a quick map of related options before doing detailed calculations. It is particularly useful at the start of a task, during review meetings, and when onboarding teammates who need a clear sequence rather than isolated links.
Common mistakes to avoid
- Jumping directly to a random tool without confirming the page-level assumptions first.
- Opening many links at once, which makes it hard to compare methods consistently.
- Copying outputs without recording input assumptions, units, and interpretation context.
- Treating summary text as final advice instead of validating with the linked detailed tool.
Interpretation and worked example
A reliable pattern is: pick one objective, open one recommended link, run a baseline case, then return and choose only one follow-up branch. If your second branch gives a conflicting direction, go back to this page and compare assumptions (units, period, constraints) before deciding. This keeps decisions traceable and avoids hidden mismatches across pages.
See also
FAQ
Which formulas does the body fat calculator use?
Choose the US Navy circumference method or the BMI-based Deurenberg equation. Both accept metric or US customary measurements and clip results to 0–75 %.
Is this body fat estimate medical advice?
No. These methods provide estimates only. Discuss health or training decisions with a clinician, registered dietitian, or certified coach.
What should I do first on this page?
Start with the minimum required inputs or the first action shown near the primary button. Keep optional settings at defaults for a baseline run, then change one setting at a time so you can explain what caused each output change.
Why does this page differ from another tool?
Different pages often use different defaults, units, rounding rules, or assumptions. Align those settings before comparing outputs. If differences remain, compare each intermediate step rather than only the final number.
How reliable are the displayed values?
Values are computed in the browser and rounded for display. They are good for planning and educational checks, but for regulated or high-stakes decisions you should validate assumptions with official guidance or professional review.