Body Fat Calculator
Body Fat Calculator (US Navy Method)
Measurements
Results
Body Fat % Categories — Men
| Category | Range |
|---|
Based on your results — what to do next:
Cross-check with BMI
Your 15.5% body fat is the gold standard, but BMI is what most health guidelines use — see both numbers side by side.
Set your calorie target to reach your goal
Losing 0.8 lbs of fat requires a sustained calorie deficit — find your exact TDEE and deficit target.
Get your macro targets
Hitting your ideal body fat of 15.0% is easier with precise protein, carb, and fat targets dialed in.
This body fat calculator uses the US Navy circumference method — the same formula used by the US military to assess fitness. Enter your weight, height, waist, neck (and hip for women) to get your body fat percentage, ACE category (Athletic / Fitness / Average / Obese), fat mass, lean mass, and how much fat to lose to reach the Fitness tier.
US Navy Body Fat Formula
The US Navy circumference method was developed to replace caliper skinfold testing with an equally accurate, easier-to-administer tape-measure protocol. It uses logarithmic ratios of body circumferences — validated against hydrostatic weighing and DEXA in studies showing ±3–4% accuracy.
| Measurement | Where to Measure | Notes |
|---|---|---|
| Waist | At the navel (belly button) | Not the narrowest point. Exhale normally. |
| Neck | Just below the larynx | Tilt chin down slightly. Tape perpendicular to spine. |
| Hip (women) | Widest point of hips/buttocks | Stand with feet together, side view. |
| Height | Standing, no shoes | Stand straight against a wall. |
Worked example (male): Height 178 cm, waist 87 cm, neck 38 cm. BF% = 495 ÷ (1.0324 − 0.19077 × log₁₀(87 − 38) + 0.15456 × log₁₀(178)) − 450 = 495 ÷ (1.0324 − 0.19077 × 1.690 + 0.15456 × 2.250) − 450 ≈ 19.1% (Average category).
💡 Pro-Tip: Measure Consistently for Accurate Tracking
Consistency matters more than absolute accuracy.Measure first thing in the morning before eating or drinking, after using the restroom. Use the same tape measure, the same body positions, and ideally the same time of day. A single measurement tells you where you are today; the trend over 4–8 weeks tells you whether your diet and exercise program is working. If you're losing weight but body fat % stays the same, you're losing both fat and muscle — consider increasing protein intake (0.7–1g per lb bodyweight) to preserve lean mass.
Body Fat Calculator FAQ
How accurate is the US Navy body fat formula?
The US Navy method has a margin of error of approximately ±3–4% body fat compared to DEXA scanning. This is comparable to bioelectrical impedance (BIA) scales and better than most consumer smart scales. The biggest source of error is inconsistent measurement technique — where exactly you place the tape measure has a larger effect than the formula itself.
What is a healthy body fat percentage?
For men: Essential fat (2–5%), Athletic (6–13%), Fitness (14–17%), Average (18–24%), Obese (25%+). For women: Essential fat (10–13%), Athletic (14–20%), Fitness (21–24%), Average (25–31%), Obese (32%+). Women naturally carry 6–8% more essential fat than men due to hormonal and reproductive biology — this is normal and healthy.
Is body fat % better than BMI?
Body fat percentage is more informative than BMI for most purposes. BMI only uses height and weight — it can't distinguish muscle from fat, so muscular athletes often appear “overweight” by BMI even with low body fat. Body fat % directly measures your actual fat-to-lean ratio. That said, BMI is simpler to calculate and is what most medical guidelines (heart disease risk, insurance) are based on.
How do I reduce body fat without losing muscle?
The key is a moderate caloric deficit (300–500 calories/day below TDEE) paired with adequate protein intake (0.7–1g per pound of bodyweight) and resistance training. Aggressive caloric restriction (1,000+ cal/day deficit) speeds fat loss but causes significant muscle loss. Track body fat % rather than just body weight — if weight drops while body fat % stays constant or rises, you're losing muscle.
Why is my body fat different between this and my smart scale?
Smart scales use bioelectrical impedance (BIA), which is highly sensitive to hydration status. Being well-hydrated lowers the BIA reading; dehydration inflates it. The Navy tape method is more stable day-to-day because it doesn't depend on hydration. For tracking progress, pick one method and stick to it — the trend matters more than the absolute number.