Body Fat Measurement Methods Comparison

Compare 6 body fat measurement methods side by side. Navy vs DEXA vs BIA vs skinfold. See accuracy, cost, time, and recommendations.

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DEXA Scan
Grade: A

Dual-energy X-ray absorptiometry. The clinical gold standard. Uses low-dose X-rays to measure bone density, lean mass, and fat mass separately. Most accurate method available.

Accuracy
±1-2%
Cost
$100-250
Time
15-30 min
Pros: Highest accuracy (±1-2%), measures regional body fat distribution, also provides bone density data
Cons: Expensive ($100-250 per scan), requires clinic visit, not practical for frequent tracking
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Hydrostatic Weighing
Grade: A-

Underwater weighing. Measures body density by comparing your weight on land vs. underwater. Fat is less dense than water and muscle/bone, so body density reveals fat percentage.

Accuracy
±2-3%
Cost
$50-100
Time
30-45 min
Pros: Very accurate (±2-3%), long-established method, used in research settings
Cons: Requires specialized facility, uncomfortable (full submersion), expensive for regular use
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US Navy Method
Grade: B+

Uses a tape measure at neck, waist, and hips. Developed by the US Navy in the 1980s and validated on thousands of service members. Our calculator uses this method.

Accuracy
±3-4%
Cost
FREE
Time
2 min
Pros: Free, only needs a $3 tape measure, 2 minutes, not affected by hydration, results are very reproducible
Cons: Less accurate for very lean (<8%) or very muscular individuals, requires accurate measurement technique
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Skinfold Calipers
Grade: B

Pinches and measures the thickness of subcutaneous fat at specific body sites (3-7 sites depending on the formula). Estimates total body fat from these measurements.

Accuracy
±3-5%
Cost
$10-30
Time
10-15 min
Pros: Inexpensive ($10-30 one-time), good for tracking changes over time, not affected by hydration
Cons: Requires skill and practice — accuracy depends on technique, same person should measure each time, can be uncomfortable
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BIA Smart Scale
Grade: C-

Bioelectrical impedance analysis. Sends a tiny electrical current through your body. Fat resists current more than muscle, so impedance estimates body fat. Found in most smart scales.

Accuracy
±5-10%
Cost
$20-100
Time
30 sec
Pros: Convenient, fast (30 seconds), can measure daily, relatively cheap ($20-100 one-time)
Cons: Very unreliable — hydration status can swing readings ±10% daily. Drinking 500ml water = 2-3% error. Not useful for day-to-day tracking. Only useful for long-term trend (months).
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BMI Formula
Grade: D

Body Mass Index uses only height and weight. Estimates body fat through the Deurenberg formula (BMI + age + gender = estimated BFP). The least accurate but simplest method.

Accuracy
±8-15%
Cost
FREE
Time
10 sec
Pros: Free, instant, no measurements needed beyond height and weight
Cons: Cannot distinguish between muscle and fat — classifies muscular athletes as obese and skinny-fat individuals as healthy. Use only as a rough starting point.
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Body Fat Measurement Methods Compared: Accuracy, Cost & Time | Navy vs DEXA vs BIA