Get your BMI and body fat percentage instantly. Free, no signup required. Science-backed US Navy method.
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Discover PuraviveBody Mass Index categories according to the World Health Organization.
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Malnutrition, osteoporosis risk |
| 18.5 – 24.9 | Normal Weight | Lowest health risk |
| 25.0 – 29.9 | Overweight | Increased risk of heart disease, diabetes |
| 30.0 – 34.9 | Obese Class I | High risk of metabolic disease |
| 35.0 – 39.9 | Obese Class II | Very high risk |
| 40.0+ | Obese Class III | Extremely high risk |
BMI does not distinguish between muscle and fat mass. Athletes and muscular individuals may have a high BMI with low body fat.
Healthy body fat ranges vary by gender. Based on the American Council on Exercise (ACE) guidelines.
| Category | Body Fat % |
|---|---|
| Essential Fat | 2 – 5% |
| Athletes | 6 – 13% |
| Fitness | 14 – 17% |
| Average | 18 – 24% |
| Obese | 25%+ |
| Category | Body Fat % |
|---|---|
| Essential Fat | 10 – 13% |
| Athletes | 14 – 20% |
| Fitness | 21 – 24% |
| Average | 25 – 31% |
| Obese | 32%+ |
Everything you need to understand and track your body composition.
Instantly calculate your Body Mass Index based on height and weight. Free, no signup needed.
Estimate body fat using the proven US Navy circumference method. More accurate than BMI alone.
Log your weight, body fat, and BMI over time. See trends and track progress toward your goals.
See exactly how much of your weight is fat versus lean tissue. Understand your true body composition.
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Try Java Burn →Why body fat percentage matters more than the number on the scale.
Your body is composed of two main types of tissue: lean mass (muscles, bones, organs, water) and fat mass (essential and storage fat). Two people can weigh the same but look completely different depending on their ratio of lean to fat tissue.
BMI is a simple height-to-weight ratio that doesn't distinguish between muscle and fat. A muscular athlete could have a "overweight" BMI despite having very low body fat. Body fat percentage gives a much more accurate picture of your health and fitness level.
The US Navy circumference method estimates body fat using measurements of the neck, waist (and hips for women) along with height. It was developed for military fitness assessments and has been validated against more expensive methods like DEXA scans and hydrostatic weighing. While not as precise as lab methods, it's accurate enough for tracking trends over time.
Essential fat is the minimum amount needed for normal physiological function — approximately 2-5% for men and 10-13% for women. Going below these levels is dangerous. Storage fat is the energy reserve stored in adipose tissue. Some storage fat is normal and healthy, but excess storage fat increases the risk of metabolic disease, heart disease, and diabetes.
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Answers to common body fat and BMI questions.
For men, a healthy body fat percentage is generally between 10-24%, with athletes typically at 6-13%. For women, a healthy range is 20-31%, with athletes at 14-20%. Essential fat (the minimum needed for health) is 2-5% for men and 10-13% for women. Going below essential fat levels is dangerous.
The US Navy method is generally accurate within 1-3% of laboratory methods like DEXA scans for most people. It's most accurate for individuals in the average body fat range. Very lean or very obese individuals may see larger deviations. For best accuracy, measure at the same time of day, consistently.
Body fat percentage is a much better indicator of health and fitness than BMI alone. BMI is a simple screening tool that doesn't distinguish between muscle and fat. Someone with significant muscle mass could have a "overweight" BMI while being very lean. Body fat percentage gives you the actual ratio of fat to total body weight.
Measure your waist at the level of your navel (belly button), standing relaxed. Don't suck in your stomach. For the neck, measure just below the larynx (Adam's apple), perpendicular to the long axis of the neck. For women, also measure hips at the widest point of the buttocks.
Fat mass is the total weight of fat tissue in your body (both essential and storage fat). Lean mass is everything else — muscle, bone, water, organs, and connective tissue. When people say they want to "lose weight," they usually mean they want to lose fat mass while preserving (or increasing) lean mass.
For tracking progress, measuring once per week or every two weeks is ideal. Body fat doesn't change overnight, and daily fluctuations in hydration and food intake can affect measurements. Measure at the same time of day (morning, before eating) for the most consistent results.
Yes! This is called body recomposition. By building muscle while losing fat, your weight may stay the same (or even increase) while your body fat percentage drops. This is why body fat percentage is a better metric than scale weight for tracking fitness progress.
Excess body fat — especially visceral fat around the organs — is strongly linked to type 2 diabetes, heart disease, stroke, certain cancers, and metabolic syndrome. Maintaining a healthy body fat percentage significantly reduces these risks and improves energy levels, hormonal balance, and overall well-being.
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