Value Engine

Body Fat Calculator

What is my body fat percentage?

Estimate your body fat percentage using the US Navy Method.

Measurements

Calculate Body Fat

Enter your measurements on the left to estimate your body fat percentage.

The results provided by this tool are for educational and informational purposes only. This is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

Recommended Next Steps

Continue your journey with these related tools

Lean Body Mass

Estimate lean mass vs fat mass.

Macro & Calorie Planner

Plan weight loss with custom macros.

BMI Calculator

Calculate your Body Mass Index.

The Science of Body Composition

Key Insights & Concepts

This calculator uses the US Navy circumference method. While not as precise as a clinical scan, it is widely considered the most accurate "home" method, with a correlation of 0.85 against hydrostatic weighing. It works because fat distribution follows predictable patterns relative to height and skeletal size.

Body Fat vs. BMI

BMI is a simple calculation of weight divided by height. It cannot tell the difference between 20lbs of fat and 20lbs of muscle.
Body Fat Percentage is the "source of truth." It tells you exactly how much of your mass is metabolically active tissue (lean mass) vs energy storage (fat mass).

Measurement Methods Compared

Gold Standard
DEXA Scan / Hydrostatic Weighing

Clinical grade accuracy (+/- 1%). DEXA uses X-rays to map bone, fat, and muscle. Expensive and requires a lab visit.

This Tool
US Navy Method (Tape Measure)

Accuracy +/- 3-4%. Best balance of free, fast, and "good enough" for tracking trends over time.

Variable Accuracy
Bioimpedance (Smart Scales)

Sends electricity through feet. Highly variable based on hydration. Drinking a glass of water can change your result by 2%.

Understanding Fat Types

  • Essential Fat: Found in bone marrow, organs, and CNS. Required for life. Men need 2-5%; Women need 10-13% for hormonal function.
  • Subcutaneous Fat: Located under the skin. The "inch you can pinch." Relatively harmless metabolically but aesthetically annoying.
  • Visceral Fat: Deep belly fat surrounding organs. Highly inflammatory and linked to disease. The US Navy method is particularly sensitive to this via the waist measurement.

How to Measure Accurately

Neck

Measure below the Adam's apple (larynx) at the narrowest point.

Waist

Men: At navel. Women: At narrowest point (above navel).

Hips

Women only: At the widest part of the buttocks.

Consistent Tracking

Don't measure every day. Water retention fluctuates daily. Measure once a week, first thing in the morning, before eating/drinking, after using the bathroom.

Frequently Asked Questions

Studies show the Navy Method is accurate within 3-4% for most of the population. It correlates strongly (r=0.85) with hydrostatic weighing. However, it can be less accurate for outliers—extrememly muscular bodybuilders (overestimates fat) or elderly individuals with severe muscle atrophy (underestimates fat).
Tape placement and tension are critical. Moving the tape just 0.5 inches up or down the waist can change the result by 1-2%. For consistency, always measure at the exact same landmarks (e.g., naval) and apply the same tension (snug, not tight).
Essential fat is required for life (bone marrow, organs, nerves). Men need ~3%, women need ~12%. Storage fat is the energy accumulated in adipose tissue. Dipping into essential fat levels is dangerous and can cause organ failure and hormonal shutdown.
The neck is a unique body part that generally does not store significant fat compared to the waist, but does grow with skeletal frame and muscle mass. Detailed studies found that using the neck circumference as a proxy for 'lean body frame' improved the formula's accuracy significantly.
Smart scales are convenient but highly variable. They rely on sending a small electrical current through your legs. Hydration status (drinking water, sweating, salt intake) can swing your result by 5% in a single day. The Navy Tape method is generally more consistent for tracking long-term trends.
Medical term: Normal Weight Obesity. This describes a person with a normal BMI but high body fat percentage and low muscle mass. They face similar metabolic risks (diabetes, heart disease) as overweight individuals. The goal for them is 'body recomposition' (build muscle, lose fat) rather than just weight loss.
A safe and sustainable rate is 0.5% to 1% of body fat per week. Losing faster than this usually indicates muscle loss or dehydration, which damages your metabolism and leads to the 'yo-yo' effect.
No, a pound is a pound. However, muscle is much more *dense* than fat. One pound of muscle takes up about 18% less space than one pound of fat. This is why you can look slimmer and wear smaller clothes even if the scale number hasn't changed.
For men 20-40, 8-19% is healthy; 41-60, 11-21% is healthy. For women 20-40, 21-32% is healthy; 41-60, 23-33% is healthy. Nature intends for body fat to increase slightly with age to protect bone density.
Biology prioritizes reproduction. Women store extra essential fat in the breasts, pelvis, hips, and thighs to support potential pregnancy and lactation. This fat is hormonally regulated and much harder to lose than male abdominal fat, but it is also less damaging to heart health.