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.
Category ranges
These ranges are typical reference values for each category. Use your full context (training status, age, hydration, method) when interpreting results.
| Category | Range |
|---|
Category visualization
This visual bar shows where the estimated body fat percentage sits across category bands. It helps you spot trend changes and boundary effects.
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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When to use this calculator
Use this page when you want a quick body-composition estimate from measurements you can collect yourself. It is best for comparing one method over time, not for replacing a clinical scan or diagnosing health status.
Recommended workflow
- Choose the formula first: US Navy for circumference-based estimates, BMI-based Deurenberg when you only have height and weight.
- Measure consistently each time, especially waist, neck, and hip where required.
- Compare trends with the same method before you compare your result with another tool or device.
When to open a different page
- Open BMI when you only need a screening category from height and weight.
- Open Calorie Planner when your next question is calorie intake or goal timing.
- Use a clinical method such as DEXA or professional assessment when body-composition precision matters.
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.
Which method should I use first?
Use the US Navy method if you can measure circumference carefully. Use the BMI-based estimate when you only have height, weight, age, and sex and need a fast screening result.
Why does my result differ from a smart scale or another site?
Each method uses different assumptions and body measurements. Compare the same formula and the same unit inputs before deciding whether the difference is meaningful.
How should I interpret the number?
Treat it as an estimate for tracking trends. Look at changes over time with the same method rather than reading one percentage as a clinical verdict.