Body Fat Calculator (US Navy Method)

How body fat impacts health

Body fat percentage and body weight are not the same. Scale weight alone does not tell you how much of your body is fat versus muscle, bone, or water. Two people can weigh the same but have very different body compositions—and different health risks. Body fat percentage gives a clearer picture of your actual composition and is a useful metric to track alongside weight when you care about fitness and long-term health.

Very high body fat is associated with greater risk of heart disease, type 2 diabetes, high blood pressure, and some cancers. Excess fat, especially around the waist, can affect hormones and inflammation. That does not mean that everyone in the "average" or "obese" category will develop these conditions—risk depends on genetics, lifestyle, and many other factors. Still, lowering body fat through sustainable diet and exercise is often recommended by health professionals when levels are high.

Extremely low body fat also carries risks. For men, dropping into the "essential" range (around 2–5%) and for women well below healthy athletic ranges can disrupt hormones, weaken the immune system, and increase injury risk. Athletes sometimes push body fat very low for competition, but staying there long-term is not necessary for health and can be harmful. Adequate fat is needed for vitamin absorption, hormone production, and overall function.

For most people, tracking trends matters more than a single measurement. Your exact percentage on any given day can vary with hydration, timing, and measurement error. What matters is whether your body fat is moving in the right direction over weeks and months when you combine this calculator with consistent habits. Use it for general awareness and progress, not as a sole diagnosis. Always consult a healthcare provider for personalized advice.

Compare measurement methods

The US Navy method offers a good balance of accuracy and convenience for home use. BMI is quick but does not distinguish fat from muscle. Skinfold calipers can be accurate when used by someone trained; DEXA is the most accurate but is typically used in clinics or research. For most people, using one method consistently (e.g. this calculator) to track trends over time is more useful than chasing the most precise single number.

Tips to reduce body fat safely

Sustainable changes tend to work better than quick fixes. Here are evidence-based areas to focus on:

• •Nutrition basics: Prioritize whole foods, enough protein, and a modest calorie deficit if you need to lose fat. Avoid extreme restriction; it is hard to maintain and can backfire.
• •Strength training: Building or preserving muscle helps your metabolism and improves body composition. Include resistance training at least two days per week.
• •Sleep and hydration: Poor sleep and dehydration can affect hunger, recovery, and how your body stores fat. Aim for consistent sleep and adequate water intake.
• •Consistency over quick fixes: Small habits you can keep for months or years beat short, intense efforts. Track trends with tools like this calculator and adjust gradually.

This is general guidance only. For a plan tailored to your health and goals, consult a doctor or registered dietitian.