Body Fat Calculator
Estimate your body fat percentage and lean body mass online using the US Navy tape measure method.
Enter your tape measurements and click Calculate to estimate your body fat percentage using the US Navy Method.
Free Body Fat Calculator (Tape Measure Method)
Estimate your body fat percentage using the US Navy tape measure method. All you need is a flexible measuring tape to measure your waist, neck, and (for women) hips — no calipers, smart scale, or DEXA scan required. This is one of the most accessible ways to track fat loss beyond just looking at the scale.
How to Measure (Body Fat Tape Measure Guide)
- Measure your neck circumference just below the larynx.
- Measure your waist at the navel (men) or the narrowest point (women).
- Women also measure hip circumference at the widest point.
- Enter your height, gender, and these measurements to get your estimated body fat %.
- Keep the tape snug but not compressing the skin, and measure at the same time of day for consistent tracking.
Example
A man who is 178cm tall with a 90cm waist and 38cm neck gets an estimated body fat percentage in the "average" range using the US Navy formula.
Common Use Cases
- Tracking body composition changes over time, alongside or instead of weight alone.
- Getting a body fat estimate without calipers, a scale with sensors, or a DEXA scan.
FAQs
How accurate is the US Navy body fat calculator?
It's a reasonable estimate for most people — typically within a few percentage points of more precise methods like DEXA scans or hydrostatic (underwater) weighing — but it is an estimate, not a lab measurement. Because it infers body fat from circumference measurements rather than measuring fat tissue directly, accuracy drops for very lean athletes, very muscular individuals, and people with unusual body-fat distribution. Use it consistently (same tape, same technique, same time of day) to track trends rather than treating any single reading as exact.
Is the Navy body fat calculator accurate enough to trust?
For general fitness tracking, yes — it's a well-studied, widely used method that's accurate enough to show whether you're gaining or losing fat over weeks and months. If you need clinical precision (e.g. for a medical or research purpose), a DEXA scan or hydrostatic weighing will give a more exact number.
What do I need for this tape measure body fat calculator?
Just a flexible measuring tape and your height. You'll measure neck and waist circumference (plus hip circumference for women) and enter them above — no calipers, scale, or equipment beyond the tape.