Lichaamsvet Calculator — US Navy Methode

The Body Fat Calculator estimates your body fat percentage using the US Navy circumference method — a validated, non-invasive approach developed by the United States Navy and based on research by Hodgdon and Beckett (1984). Unlike BMI, which uses only height and weight, this method uses anatomical circumference measurements to estimate body composition directly, providing a more meaningful assessment of health and fitness status.

Body fat percentage is the proportion of your total body weight that is fat tissue. It includes essential fat (the minimum fat required for normal physiological function — approximately 3–5% in men and 10–13% in women) and storage fat (energy reserves and cushioning around organs). Knowing your body fat percentage reveals what BMI cannot: whether excess weight is fat or muscle, and whether low weight reflects leanness or muscle loss.

This calculator requires neck and waist measurements for men, and neck, waist, and hip measurements for women. The sex difference exists because men and women have different fat distribution patterns: men tend toward abdominal fat concentration (android pattern), while women naturally store more fat in the hip and thigh region (gynoid pattern). The formula accounts for both patterns to provide sex-appropriate estimates.

Example 1 — Male, 180 cm, 85 kg, neck 39 cm, waist 88 cm: Body Density = 1.0324 − 0.19077 × log10(88−39) + 0.15456 × log10(180) = 1.0324 − 0.19077 × 1.690 + 0.15456 × 2.255 = 1.0324 − 0.3224 + 0.3485 = 1.0585 Body Fat % = (495 ÷ 1.0585) − 450 = 467.5 − 450 = 17.5% Fat mass: 85 × 0.175 = 14.9 kg | Lean mass: 70.1 kg | Category: Acceptable

Example 2 — Female, 165 cm, 65 kg, neck 33 cm, waist 72 cm, hip 98 cm: Body Density = 1.29579 − 0.35004 × log10(72+98−33) + 0.22100 × log10(165) = 1.29579 − 0.35004 × log10(137) + 0.22100 × 2.2175 = 1.29579 − 0.35004 × 2.1367 + 0.48987 = 1.29579 − 0.74788 + 0.48987 = 1.03778 Body Fat % = (495 ÷ 1.03778) − 450 ≈ 477.0 − 450 = 27.0% Fat mass: 17.6 kg | Lean mass: 47.4 kg | Category: Acceptable

Body fat percentage reveals health information that weight and BMI cannot provide. Two people can weigh exactly the same and have the same BMI while having radically different body compositions: one with 15% body fat and high muscle mass, another with 35% body fat and minimal muscle. The first is metabolically healthy; the second carries substantially elevated risks of type 2 diabetes, cardiovascular disease, and metabolic syndrome. Weight and BMI cannot distinguish them — body fat percentage can.

Elevated body fat — particularly abdominal and visceral fat — is directly linked to chronic disease risk. The World Health Organization identifies excess body fat as a major risk factor for cardiovascular disease, hypertension, type 2 diabetes, sleep apnea, and multiple cancers. Specifically, visceral fat (fat stored around the liver, pancreas, and intestines) is metabolically active tissue that releases inflammatory cytokines and disrupts insulin signaling — it is far more dangerous than subcutaneous fat at equivalent total percentages.

Conversely, tracking body fat percentage (rather than just weight) during a diet and exercise program gives a more accurate picture of progress. It is common and entirely normal for the scale to stay the same or even increase slightly during the first weeks of a strength training program, while body fat percentage decreases and lean mass increases. A person who relies on scale weight alone may abandon a program that is actually working. Body fat percentage tracking reveals the true story.

The US Navy method has a standard error of approximately 3–4 percentage points compared to underwater weighing. This means a calculated result of 20% body fat could reflect a true value between 16% and 24%. The formula is most accurate for individuals with average body proportions and fat distribution. For individuals with unusual body shapes, very low or very high body fat, or significant muscular development, accuracy decreases.

The formula is sensitive to measurement error. A 1 cm error in waist measurement changes the result by approximately 0.5–1.0 percentage points. This is why consistency of measurement technique — same time of day, same body posture, same tape position — is more important than absolute precision. The value of body fat tracking comes from trend data over time, not from single-point absolute accuracy.

Importantly, the US Navy formula does not distinguish between visceral and subcutaneous fat — the location of fat is not captured, only the total amount. Since visceral fat carries much higher metabolic risk than subcutaneous fat at the same total body fat percentage, two individuals with the same calculated body fat percentage can have substantially different health risk profiles. Waist circumference alone remains a better predictor of cardiovascular risk than body fat percentage for this reason.