Body Fat Calculator

What Is Your Body Fat Percentage?

Body fat percentage is the proportion of your total body weight that's made up of fat tissue. Unlike BMI, which only uses height and weight, body fat percentage distinguishes between fat mass and lean mass (muscle, bones, organs, water) — giving you a far more accurate picture of your body composition and health.

Our calculator uses the U.S. Navy Method, a well-validated circumference-based formula that estimates body fat from simple tape measurements. You'll need your neck circumference, waist circumference, and (for women) hip circumference, along with your height. The calculation takes seconds and requires only a flexible measuring tape.

Healthy ranges: For men, 10–20% body fat is considered healthy, with 15% being typical for a fit adult male. For women, 18–28% is healthy, with 23% being typical for a fit adult female. Essential fat (the minimum needed for physiological function) is approximately 3–5% for men and 10–13% for women.

How the U.S. Navy Method Works

The U.S. Navy developed this formula in the 1980s to assess the body composition of service members without expensive equipment. It uses the relationship between circumference measurements at specific body sites to estimate total body fat.

For men: Body fat % = 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76

For women: Body fat % = 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387

The formula works because fat distribution correlates with circumference at these sites. A larger waist relative to neck and height indicates higher body fat. Adding hip circumference for women accounts for sex-specific fat distribution patterns.

Accuracy: The Navy Method estimates body fat within 3–4% of hydrostatic weighing (underwater weighing) for most people. It's most accurate for individuals in the normal-to-moderately-overweight range and less precise at extremes (very lean or very obese). For a free, equipment-free estimate, it's one of the best available methods.

How to measure correctly: Use a flexible tape measure (not elastic). Measure the neck just below the larynx (Adam's apple), sloping slightly downward at the front. Measure the waist at the narrowest point (usually at the navel or just above it). Measure hips at the widest point of the buttocks. Pull the tape snug but not tight — it should not compress the skin. Measure on bare skin or thin clothing. Take each measurement twice and use the average.

Body Fat Categories

Essential fat (Men: 2–5%, Women: 10–13%): The minimum fat needed for basic physiological function — hormone production, organ insulation, vitamin absorption, and cellular structure. Dropping below essential fat is dangerous and associated with hormonal disruption, immune suppression, and organ damage. Only competitive bodybuilders reach this range, and only temporarily for competitions.

Athletes (Men: 6–13%, Women: 14–20%): Lean and muscular with visible muscle definition. Maintaining this range year-round requires disciplined nutrition and consistent training. Many competitive athletes in aesthetic sports (bodybuilding, physique, gymnastics) and endurance sports operate in this range.

Fitness (Men: 14–17%, Women: 21–24%): A healthy, fit appearance with some muscle definition visible, especially in good lighting. This is a sustainable long-term range for people who exercise regularly and eat a balanced diet. Most fitness influencers and recreational athletes fall here.

Average (Men: 18–24%, Women: 25–31%): The typical range for adults who are not specifically focused on fitness. Health risks are moderate, and some excess fat is present but not necessarily problematic — other health markers (blood pressure, blood sugar, cholesterol) matter more at this level than body fat alone.

Obese (Men: 25%+, Women: 32%+): Elevated body fat associated with increased risk of metabolic disease, cardiovascular problems, joint issues, and certain cancers. At this level, reducing body fat through dietary changes and exercise is medically recommended.

Body Fat Measurement Methods Compared

DEXA scan (Dual-Energy X-ray Absorptiometry) is the gold standard for body composition. It measures fat, muscle, and bone density throughout the body with high precision (±1–2%). Cost: $75–$150 per scan. Available at medical facilities and some specialty fitness clinics. Best for tracking changes over time with high accuracy.

Hydrostatic (underwater) weighing measures body density by comparing your weight on land to your weight submerged in water. Historically the reference standard, though DEXA has largely replaced it. Accuracy: ±1.5–2.5%. Requires specialized equipment and is less widely available.

Skinfold calipers pinch skin and subcutaneous fat at 3–7 body sites. A trained technician can achieve accuracy within 3–4%. Results vary significantly between technicians — for reliable tracking, use the same person each time. Inexpensive ($10–$30 for calipers) but technique-dependent.

Bioelectrical impedance (BIA) sends a small electrical current through the body. Scales and handheld devices using BIA are widely available ($20–$200). Accuracy is moderate (±3–5%) and heavily affected by hydration, recent meals, exercise, and time of day. Best used for trend tracking (measure at the same time under the same conditions each time) rather than absolute accuracy.

Circumference methods (like the Navy Method used in this calculator) require only a tape measure. Accuracy: ±3–4%. Free and accessible to everyone. Less precise than DEXA or hydrostatic weighing but surprisingly reliable for most people.

How to Reduce Body Fat

Calorie deficit is fundamental. To lose fat, you must consume fewer calories than you burn. A deficit of 500 calories/day produces approximately 1 lb of fat loss per week. Use our TDEE calculator to determine your maintenance calories, then subtract 500.

Protein intake protects muscle. During a calorie deficit, your body breaks down both fat and muscle for energy. Consuming 0.7–1.0 grams of protein per pound of body weight preserves muscle mass and keeps metabolic rate higher. High protein also increases satiety, making the deficit easier to sustain.

Resistance training is non-negotiable. Lifting weights or performing bodyweight resistance exercises signals your body to preserve muscle during a calorie deficit. Without resistance training, 25–30% of weight lost can come from muscle. With proper training and protein, muscle loss drops to 5–10%.

Cardiovascular exercise supplements the deficit. Cardio burns additional calories and improves cardiovascular health but is secondary to diet for fat loss. Walking 30–60 minutes daily, cycling, swimming, or any sustained activity adds 200–500 calories of expenditure. Don't rely on cardio alone — it's extremely difficult to out-exercise a poor diet.

Sleep and stress matter. Poor sleep (less than 7 hours consistently) increases cortisol, reduces insulin sensitivity, and increases appetite — all of which promote fat storage, particularly visceral fat. Chronic stress has similar effects. Prioritizing 7–9 hours of sleep and managing stress supports fat loss efforts significantly.