SamCalculator

Body Fat Calculator

Estimate your body fat percentage using the accurate U.S. Navy method with category analysis and personalized insights.

years
kg
cm
Body Measurements
at narrowest
cm
at navel
cm

How to measure correctly

Neck:Measure just below the larynx (Adam's apple), sloping slightly downward.
Waist:Measure horizontally at the navel / belly button level.

Fill in your measurements to get your body fat analysis.

What is Body Fat Percentage?

Body fat percentage is the proportion of your total body weight that comes from fat tissue. It's a far more meaningful health metric than weight alone — two people of the same weight and height can have very different body compositions. An athlete and a sedentary person might weigh the same, but one could have 10% body fat while the other has 28%.

Body fat includes two types: essential fat (required for survival and hormonal function) and storage fat (accumulated energy reserves). Too little or too much of either is a health concern.

Healthy Body Fat Ranges (ACE Standards)

The American Council on Exercise (ACE) defines body fat categories for both men and women:

CategoryMenWomen
Essential Fat
2–5%10–13%
Athletes
6–13%14–20%
Fitness
14–17%21–24%
Average
18–24%25–31%
Obese
25%+32%+

The U.S. Navy Body Fat Formula

This calculator uses the U.S. Navy circumference method — one of the most widely validated field methods for estimating body fat. It requires only a tape measure and is accurate to within 3–4% of DEXA scan results for most people.

For Men

BF% = 86.010 × log₁₀(waist − neck)
      − 70.041 × log₁₀(height)
      + 36.76

For Women

BF% = 163.205 × log₁₀(waist + hip − neck)
      − 97.684 × log₁₀(height)
      − 78.387

All measurements in centimeters. For US units, measurements are converted to cm before computation.

Body Fat vs BMI — What's the Difference?

BMI (Body Mass Index)

BMI calculates a ratio of weight to height. It's simple to compute but cannot distinguish between fat and muscle. A muscular athlete may have a "overweight" BMI despite very low body fat.

Formula: weight(kg) ÷ height(m)²

Body Fat % (Navy Method)

Body fat % directly estimates fat tissue. It accurately reflects fitness level, metabolic health, and health risks in ways BMI cannot. Two people with the same BMI can have vastly different body compositions.

More accurate for fitness assessment

How to Reduce Body Fat

Create a calorie deficit

Consistently eating 300–500 fewer calories than you burn will result in fat loss of about 0.5 kg/week without losing muscle.

Prioritize resistance training

Lifting weights preserves and builds lean muscle mass while you lose fat, improving your body composition ratio.

Increase protein intake

Eating 1.6–2.2g of protein per kg of bodyweight preserves muscle during fat loss and keeps you fuller longer.

Add cardio strategically

Cardio burns additional calories without adding bulk. Mix steady-state and high-intensity intervals for best results.

Improve sleep quality

Poor sleep raises cortisol (fat-storing hormone) and reduces the anabolic hormones that build and preserve muscle.

Track and be consistent

Re-measure every 4–6 weeks, not daily. Fat loss is a slow process — consistency over months is what produces results.

Jackson & Pollock Ideal Body Fat (Age-Based)

The Jackson & Pollock ideal body fat ranges account for the natural increase in body fat with age. This calculator uses these values to compute your personalized "fat to lose" target.

AgeMen (ideal %)Women (ideal %)
20–2510.5%18.4%
26–3012.7%19.3%
31–3514.7%21.5%
36–4017.7%22.5%
41–4520.5%22.7%
46–5022.7%24.8%
51–5524.6%26.3%
56+26.3%27.4%

Frequently Asked Questions

It depends on gender and age. For men, 14–17% (Fitness) is considered healthy. For women, 21–24%. Athletes typically carry less. Essential fat (2–5% men, 10–13% women) is the absolute minimum needed for bodily functions — going below this is dangerous.

BMI is a rough proxy, not a direct measure. It can't distinguish fat from muscle. A very muscular person may have an 'overweight' BMI with very low body fat. Conversely, a 'normal weight' person might have high body fat (skinny-fat). Body fat percentage is a far more accurate indicator of health.

The easiest at-home method is the U.S. Navy tape measure method used in this calculator — just measure neck, waist (and hip for women). Other methods include skinfold calipers, bioelectrical impedance scales, or professional DEXA scans (most accurate but expensive).

Research shows the Navy method is accurate to within ±3–4% of DEXA scan results for most people. It's less accurate at very low (<8%) or very high (>35%) body fat percentages. For a free field method, it's one of the best available.

Women require more essential fat for hormonal function, reproductive health, and pregnancy. The essential fat range for women (10–13%) is higher than men (2–5%) because sex-specific fat stored in the breasts and pelvic region is physiologically necessary.

Lean body mass (LBM) is everything in your body that isn't fat — muscles, bones, organs, blood, water. It's calculated as: LBM = Total weight × (1 − body fat%). Increasing your LBM through resistance training raises your basal metabolic rate, making fat loss easier over time.

At a healthy pace of 0.5–1% body fat per month (achieved through a ~500 calorie daily deficit plus resistance training), losing 5% body fat takes approximately 5–10 months. Faster rates risk muscle loss. Slow and steady preserves your lean mass and keeps the fat off long-term.

Yes. Body fat naturally increases with age as muscle mass declines and metabolic rate slows. The Jackson & Pollock reference values account for this — the ideal body fat for a 55-year-old is higher than for a 25-year-old. Regular strength training is the most effective way to slow this process.

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