Body Fat Calculator
Estimate body fat percentage from tape measurements using the US Navy method; not a medical diagnosis.
Inputs
Result
Enter values on the left and select Calculate to see the result here.
What the Body Fat Calculator does
- Estimates body fat percentage from height, waist, neck, and, for female mode, hip measurements.
- Returns a formula-based estimate rounded to 1 decimal place plus a broad category label.
- Provides a cautious body-composition reference that should not be used as the only measure of health.
How to use the Body Fat Calculator
- Select male or female mode because the US Navy circumference formula uses different inputs.
- Enter height, waist, and neck measurements in centimetres; enter hip measurement as well when female mode is selected.
- Measure consistently with a flexible tape, level placement, relaxed posture, and without pulling the tape too tight.
- Click Calculate to see an estimate based on your inputs, not a medical diagnosis.
Formula / methodology used
- Uses the US Navy circumference method already implemented in this calculator.
- Male mode uses: 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450.
- Female mode uses: 495 ÷ (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.221 × log10(height)) − 450.
- Measurements are entered in centimetres and the calculator uses base-10 logarithms.
- The category label is broad context only and is generated from the calculator's internal ranges.
Example calculation
Male mode with height 180 cm, waist 90 cm, and neck 40 cm.
- waist − neck = 90 − 40 = 50 cm
- Formula denominator = 1.0324 − 0.19077×log10(50) + 0.15456×log10(180)
- Body fat estimate = 495 ÷ denominator − 450
- Round the calculated percentage to 1 decimal place
Result: The estimate is about 22.7% body fat, with the calculator's broad category shown as Average.
Common mistakes and limitations
- Small measurement errors can noticeably change the estimate.
- The US Navy method may be less accurate for some body shapes, ages, athletic builds, medical conditions, or clinical situations.
- Hydration, recent training, posture, and how tightly the tape is held can affect measurements.
- Use centimetres consistently; mixing inches and centimetres will invalidate the calculation.
Important note
This calculator provides a general body-composition estimate only. It is not a medical diagnosis and is not medical, fitness, nutritional, weight-loss, or healthcare advice.
Body Fat Calculator FAQs
Is this a medical diagnosis?
No. It is a formula-based estimate from tape measurements and is not medical, fitness, nutrition, or weight-loss advice.
Why can results vary between measurements?
Tape placement, measurement tension, posture, hydration, recent exercise, body shape, sex, age, and individual differences can all change the estimate.
Why does female mode ask for hip measurement?
The calculator's female-mode US Navy formula includes waist, hip, neck, and height, while male mode uses waist, neck, and height.
Should I use this as my only health measure?
No. Body composition is only one health-related metric. Consider broader health context and consult a qualified professional for personal advice.