Body Fat Calculator (U.S. Navy Method) for Men & Women
Estimate your body fat percentage with a tape measure using the U.S. Navy method. Enter neck, waist (and hips for women) in inches or cm.
How to measure
- Neck: measure just below the Adam's apple, with the tape sloping slightly down toward the front.
- Waist: men measure horizontally at the level of the belly button; women measure at the narrowest point of the waist.
- Hips (women only): measure around the widest part of the buttocks.
- Stand relaxed, do not suck in, keep the tape snug but not tight, and measure in the morning for consistency. Take each measurement twice and use the average.
The U.S. Navy formula
The U.S. Navy method estimates body fat from circumference measurements and height. It is typically within about 3–4 percentage points of more advanced methods such as DEXA scans for most people, which makes it a useful, free way to track changes over time.
Body fat categories
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Above average | 25%+ | 32%+ |
Categories based on the American Council on Exercise (ACE) body fat chart.
Why body fat matters more than weight
Two people with the same weight and height can look completely different depending on how much muscle and fat they carry. When you start strength training, you may lose fat and gain muscle at the same time, so your weight barely changes while your body fat percentage and waist measurement drop. That is real progress.
How to use your result
A calculator gives you a starting point, not a final answer. The most reliable way to use any fitness number is the measure → act → review loop:
- Measure: record your result today, along with your morning body weight, waist measurement and a few photos.
- Act: follow a matching plan for 2–4 weeks. Use the plan builder to get a workout program and a 7-day meal plan that fit your numbers.
- Review: compare your weekly averages and measurements. If things are moving in the right direction at a sustainable pace, keep going. If not, adjust by small amounts (100–200 calories, one extra workout, 2,000 extra steps) and review again.
US and metric units
Every HelloMyTrainer calculator works in both systems. Use the lb / ft or kg / cm switch at the top of the page; your choice is remembered on this device for all calculators and meal plans. Useful conversions: 1 kg = 2.2 lb, 1 inch = 2.54 cm, 1 foot = 30.48 cm, 1 liter = 33.8 US fluid ounces.
Who should be careful with these numbers
These calculators are designed for healthy adults aged 18 and over. They are not suitable for children or teenagers, pregnant or breastfeeding women, people with a history of eating disorders, competitive athletes with very high muscle mass, or people with medical conditions that affect weight, metabolism or fluid balance (such as heart failure, kidney disease or thyroid disorders). If any of these apply to you, please speak with your doctor or a registered dietitian before using the results.
Your privacy
We never ask for your name, email or any personal details to use our tools. The calculations run in your web browser and the numbers you type are not sent to our servers. See our Privacy Policy for details.
Frequently asked questions
How accurate is the Navy body fat method?
It is an estimate, typically within a few percentage points. It is most useful for tracking changes over time with consistent measurements.
Why do women have higher body fat?
Women need more essential fat for hormonal and reproductive health.
How often should I measure?
Every 2–4 weeks is enough to see meaningful change.
More free fitness calculators
- BMI Calculator
- Calorie Calculator
- Macro Calculator
- One Rep Max Calculator
- Water Intake Calculator
- Build My Plan
Results are estimates for healthy adults and are not medical advice.