Body Fat Calculator
This body fat calculator estimates your body fat percentage from a few tape-meas
This body fat calculator estimates your body fat percentage from a few tape-meas
How to use Body Fat Calculator
- Choose your units and sex, then grab a flexible tape measure.
- Enter your height, neck and waist measurements (plus hip for women, and weight if you want fat and lean mass).
- Read your estimated body fat percentage, category, and mass breakdown instantly.
About Body Fat Calculator
This body fat calculator estimates your body fat percentage from a few tape-measure circumferences using the U.S. Navy method — the same formula used in military fitness assessments. Men enter height, neck and waist; women also enter hip. It works in metric or imperial units, and if you add your weight it also breaks your body down into estimated fat mass and lean mass.
The result includes a fitness category (essential fat, athletes, fitness, average, or obese) based on standard ranges for your sex. The Navy method relies on where fat tends to accumulate, so it is a genuine estimate rather than a precise measurement. Accurate results depend on measuring carefully with a flexible tape at the correct spots while relaxed.
Everything runs privately in your browser. No measurements are uploaded, stored, or shared, and there is no sign-up. For clinical-grade accuracy, methods like DEXA scans or hydrostatic weighing are more reliable, and this tool is not a substitute for medical advice.
Frequently asked questions
- How accurate is the Navy body fat method?
- For most people it lands within about 3-4 percentage points of a DEXA scan, which is good for tracking changes over time. It is less reliable for very lean athletes or people with unusual body shapes. Measuring consistently at the same spots matters more than the absolute number.
- Where do I take the measurements?
- Measure your neck just below the larynx (Adam's apple), your waist horizontally at the navel, and, for women, your hips at the widest point. Keep the tape snug but not compressing the skin, stand relaxed, and don't hold your breath. Take each measurement twice and use the average.
- Why do women need a hip measurement but men don't?
- The Navy method uses two different equations. The men's formula uses waist and neck; the women's formula adds hip circumference because body fat distributes differently. Selecting your sex shows the correct fields automatically.
- Do I have to enter my weight?
- No. Weight is optional and is only used to convert your body fat percentage into estimated fat mass and lean mass. You still get your body fat percentage and category without it.
- Is my data private?
- Yes. All calculations happen locally in your browser using JavaScript. Nothing you type is sent to a server, saved, or shared, and there is no account or sign-up.
- What is a healthy body fat percentage?
- General fitness ranges are roughly 14-17% for men and 21-24% for women, with athletes lower. Essential fat (the minimum needed for health) is about 2-5% for men and 10-13% for women. These are guidelines, not medical thresholds — talk to a professional about your goals.