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Body Fat Calculator

Estimate your body fat percentage using the U.S. Navy circumference method.

Inputs

cm
cm

cm
cm

cm
cm

cm
cm

Only needed for the female formula.

Saved Scenarios

— select 2+ to compare

Body Fat

16.9%

Spark says

How it's calculated

Formula

BF%men=4951.0324−0.19077log⁡(W−N)+0.15456log⁡(H)−450BF\%_{men} = \dfrac{495}{1.0324 - 0.19077\log(W - N) + 0.15456\log(H)} - 450
W
— Waist circumference
N
— Neck circumference
H
— Height

What is the Body Fat Calculator?

The U.S. Navy method estimates body fat percentage from a few tape-measure circumferences, without needing calipers or a scan.

How to use it

  1. 1 Select your gender.
  2. 2 Enter your height, neck and waist measurements.
  3. 3 Women also enter hip circumference.

Worked examples

Male, 175cm, neck 38cm, waist 85cm

Estimated body fat is about 16.9%.

Try it

Limitations

  • •Less accurate than DEXA scans or hydrostatic weighing — a practical field estimate, not a clinical measurement.

Tips

  • 💡 Measure at the same time of day and in the same conditions each time for consistent tracking.

Frequently asked questions

How accurate is the Navy method?

It's generally within a few percentage points of more precise methods like DEXA scans for most body types, making it a reasonably reliable field estimate.

Sources & references