Body Fat Calculator – Estimate Your Body Fat Percentage
Estimate body fat percentage with the U.S. Navy circumference method.
About the Body Fat Calculator
What is the Body Fat Calculator?
A body fat calculator uses the U.S. Navy circumference method, which estimates body fat percentage from height plus waist, neck and hip measurements.
Why use this calculator?
Body fat percentage is a better picture of health than weight alone. Two people can weigh the same but have completely different body compositions.
How to use it
- Choose your gender.
- Measure and enter height, waist and neck (and hip for women) in centimetres.
- Read your estimated body fat percentage and category.
Formula
Men: 86.010·log10(waist − neck) − 70.041·log10(height) + 36.76
Tape measurements are the biggest source of error. Measure at the navel for waist, below the larynx for neck, and the widest point for hip.
Frequently Asked Questions
How accurate is the Navy method?
Within a few percentage points for most people when measured correctly, making it one of the best free field estimates.
Can I lose fat in one specific spot?
Spot reduction is a myth. Fat loss comes from an overall calorie deficit; genetics determine where it comes off first.
Is this a medical diagnosis?
No. This tool provides general wellness information only. It is not a substitute for evaluation by a qualified healthcare professional.
Why do results differ from my doctor's measurements?
Clinical measurements use calibrated equipment and professional technique. Home estimates rely on formulas and self-reported values, so small differences are normal.
How often should I recalculate?
Recheck after meaningful changes such as weight gain or loss, a new workout routine, or every few months to track trends over time.
Do these formulas apply to everyone?
Most population formulas are less accurate for athletes, pregnant people, very young children and the elderly. Use them as a general guide.
Is this calculator free to use?
Yes. Every calculator on this site is completely free, with no hidden fees, no subscriptions and no limits on how many times you can use it.
How accurate are the results?
We use standard, widely accepted formulas and calculate in your browser using double-precision arithmetic. Results are rounded for readability, so treat them as reliable estimates rather than a guarantee. Real-world factors can vary the true figure.
Can I add this calculator to my own website?
Yes. Open this calculator page and use the "Add to your website" box in the sidebar to copy a ready-made iframe snippet, then paste it into any HTML page.
Does it work on a phone or tablet?
Yes. The layout is fully responsive, so it works on desktops, laptops, tablets and mobile phones, and every input adapts to touch screens.