Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy tape-measure method. Get your fat category, lean mass, and fat mass breakdown instantly with no special equipment needed.
Measure just below the larynx, sloping downward to the front.
Enter your measurements
Fill in your height, neck, and waist circumference (plus hips for women) to calculate your body fat percentage using the U.S. Navy method.
U.S. Navy Method: This calculator uses the circumference-based formula developed by Hodgdon & Beckett (1984) for the U.S. Navy. It estimates body fat percentage from height, neck, waist (and hip for women) measurements. Results are estimates — DEXA, hydrostatic weighing, or air-displacement plethysmography provide higher accuracy.
About Body Fat Calculator
The Body Fat Calculator estimates body fat percentage using the U.S. Navy circumference method — a tape-measure formula validated against DEXA scans that requires no special equipment. It uses neck, waist and (for women) hip measurements alongside height.
The formula relates circumference differences to height, using separate equations for men and women. It offers a repeatable home estimate without calipers, scales with electrical impedance or imaging equipment.
It's a reasonable estimate for tracking trends over time, not a precise clinical measurement. Consistent tape position, posture and tension are more important for trend tracking than reacting to one isolated reading.
How Body Fat Calculator works in practice
- 1Choose your unit system: metric (cm) or imperial (inches).
- 2Enter your height, neck circumference and waist circumference. Women also enter hip circumference.
- 3Read your estimated body fat percentage and category.
- 4Measure at the same time of day and in the same way each time for consistent tracking.
Jobs this tool is built for
- Track a body-composition trend during a strength or weight-management programme.
- Compare circumference-based progress when scale weight stays relatively stable.
- Obtain a rough home estimate before discussing more precise testing with a professional.
- Repeat measurements under consistent conditions to reduce day-to-day noise.
What you can do here
- U.S. Navy circumference method
- Separate formulas for men and women
- Metric and imperial input
- Category ranges (essential, athletic, fitness, average, obese)
Limits and honest caveats
- Measurement technique matters a lot here — a loose or overly tight tape can shift the result by several percentage points. Measure at the same tension each time.
- This method is less accurate for people at the extremes of height or body composition than DEXA or hydrostatic weighing.
- This is a fitness-tracking estimate, not a medical diagnostic tool.
Common questions about Body Fat Calculator
How accurate is the Navy method?
Studies generally show it within about 3–4 percentage points of DEXA scan results for most adults — accurate enough to track trends, not precise enough for clinical decisions.
Where exactly do I measure my waist?
At the narrowest point for men (typically at or just above the navel), and at the widest point for women — measure without pulling the tape tight.
Why do women need a hip measurement too?
The formula was derived separately for each sex because fat distribution patterns differ; the women's version adds hip circumference to improve accuracy.
How often should I measure?
Weekly or less often is usually enough for trends. Measure under similar hydration, time-of-day, posture and tape-tension conditions.
This page was written by the ToolSink team to explain how Body Fat Calculator works on this site — it is not syndicated, scraped, or spun from another publisher. How we write tool guides · Site updates · About ToolSink.
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