Body Fat Calculator
Estimate your body fat percentage, fat mass and lean body mass from tape measurements using the U.S. Navy method.
Body Measurements
Uses circumference measurements (neck, waist, hip) - most accurate
Feet
Inches
Measure around the neck, just below the Adam's apple
Measure at the narrowest point, usually just above the navel
📏 Measurement Tips
- • Measure in the morning before eating
- • Keep tape measure snug but not tight
- • Take measurements at the same time of day
- • Use a flexible tape measure
- • Have someone help you for accuracy
Body Fat Results
Body Fat Percentage
Athletic range
Body Fat Mass
Fat weight
Lean Body Mass
Muscle, bone, organs
Body Fat Categories (Men)
Method Details
Body Fat Tips
- • Focus on overall health, not just body fat percentage
- • Combine cardiovascular and strength training
- • Diet accounts for 70-80% of body composition changes
- • Take progress photos and measurements regularly
- • Consider professional body composition analysis
How it works
Body-fat percentage tells you how much of your weight is fat versus lean mass (muscle, bone, water) — a far better health signal than weight or BMI alone. This calculator uses the U.S. Navy method, which estimates body fat from a few tape-measure circumferences and your height.
U.S. Navy method (men)
%BF = 86.010·log₁₀(waist − neck) − 70.041·log₁₀(height) + 36.76
- waist
- waist circumference (women also measure hips)
- neck
- neck circumference
- height
- standing height (same units as the circumferences)
Worked example
- Man, height 70 in
- Waist 34 in, neck 16 in
- log₁₀(34 − 16) = log₁₀(18) ≈ 1.255
- %BF = 86.010×1.255 − 70.041×log₁₀(70) + 36.76
Body fat ≈ 15% — in the “fitness” range for men.
Good to know
- Healthy ranges differ by sex: roughly 10–20% for men and 18–28% for women; essential fat (the minimum) is ~3% and ~12% respectively.
- The Navy method is convenient but approximate. Calipers, bioelectrical impedance (BIA) scales, and DEXA scans get progressively more accurate (and expensive).
- Track the trend over weeks rather than obsessing over a single reading — measurement noise can swing any one estimate by a few points.
Related Calculators
Frequently Asked Questions
What does body fat percentage mean?
Body fat percentage is the share of your total body weight that is fat, with the rest being lean mass — muscle, bone, organs and water. Two people at the same weight and BMI can have very different body fat percentages, which is why it is a better indicator of body composition and health risk than weight alone. Some fat is essential: it cushions organs, stores energy and supports hormone production.
What is a healthy body fat percentage for men and women?
The American Council on Exercise (ACE) categories are: essential fat 2–5% for men and 10–13% for women; athletes 6–13% (men) and 14–20% (women); fitness 14–17% (men) and 21–24% (women); acceptable 18–24% (men) and 25–31% (women); obese 25% or more (men) and 32% or more (women). Women naturally carry more essential fat than men for reproductive and hormonal reasons, so the healthy ranges sit several points higher.
How does the U.S. Navy tape method compare with calipers or a DEXA scan?
The Navy method estimates body fat from tape measurements — neck, waist, height, plus hips for women — using a logarithmic formula. It needs nothing but a tape measure and is typically within about 3–4 percentage points of a lab reading. Skinfold calipers pinch fat at several sites and are a little more accurate in trained hands. Bioelectrical impedance scales are quick but sensitive to hydration. DEXA scans are the practical gold standard, separating fat, lean mass and bone, but require a clinic visit.
What does this calculator measure?
By default it applies the U.S. Navy circumference formula to your height, neck and waist measurements (and hips if you are female) to estimate your body fat percentage, then reports your fat mass, lean body mass and which ACE category you fall into. Alternative methods — the pre-2023 U.S. Army tape formula, a BMI-based estimate, YMCA and Covert Bailey — are also available for comparison. All of them are estimates, not diagnoses: measure at the same time of day, keep the tape snug but not compressing, and watch the trend across weeks rather than any single reading.
How often should I exercise?
The WHO recommends at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic activity per week.
What is a balanced diet?
A balanced diet includes variety from all food groups: fruits, vegetables, whole grains, lean proteins, and healthy fats.
How much water should I drink?
General recommendation is 8-10 glasses (2-2.5 liters) per day, adjusted for activity level and climate.
How important is sleep?
Sleep is crucial for physical recovery, mental health, and overall wellbeing. Adults need 7-9 hours nightly.