Estimate your body fat percentage using the U.S. Navy method — just a tape measure, no gym equipment needed.
kg
lb
cm
ft
in
cm
cm
cm
—
EssentialAthleticFitnessObese
Fat mass (enter weight)
—
Lean mass (enter weight)
—
Body Fat Percentage Categories
American Council on Exercise (ACE) body fat classification for adults.
Category
Men
Women
Essential fat
2 – 5%
10 – 13%
Athletic
6 – 13%
14 – 20%
Fitness
14 – 17%
21 – 24%
Acceptable
18 – 24%
25 – 31%
Obese
25% and above
32% and above
Healthy body fat ranges by sex
Frequently Asked Questions
About body fat percentage and how to measure it.
The U.S. Navy method estimates body fat percentage using simple circumference measurements — waist, neck, and hips (for women) — along with height. It was developed for practical use in military fitness assessments and is considered reasonably accurate for most adults, with a typical margin of error of 3–4%.
Use a flexible tape measure and measure directly on skin, not over clothing. For the waist, measure at the level of your navel while relaxed (not sucked in). For the neck, measure just below the larynx (Adam's apple), sloping slightly downward at the front. For hips (women), measure at the widest point. Take each measurement twice and use the average.
Body fat percentage and BMI measure different things. BMI uses only height and weight, while body fat percentage directly estimates the proportion of fat in your body. Body fat percentage is generally more informative for athletes and those with high muscle mass, but BMI is easier to measure and useful for population-level screening. Using both together gives the most complete picture.
For men, a healthy body fat range is generally considered to be 8–19%, with athletic individuals typically falling in the 6–13% range. For women, healthy ranges are approximately 21–33%, with athletes typically at 14–20%. These ranges vary with age — older adults tend to carry slightly more body fat as a natural part of ageing.
Reducing body fat requires a combination of a moderate calorie deficit (eating slightly less than you burn) and regular physical activity, particularly strength training to preserve muscle mass. Crash diets tend to cause muscle loss alongside fat loss, which can actually worsen your body composition over time. Slow, consistent progress — around 0.5 kg per week — typically gives the best long-term results.
How This Calculator Works: The U.S. Navy Method
This calculator uses the U.S. Navy circumference method, developed for practical body composition assessment in military settings. Unlike DEXA scans or hydrostatic weighing, it requires only a flexible tape measure — no specialist equipment needed.
The method works by estimating body fat from body circumference measurements, which correlate with fat distribution patterns. The formulas used are:
The typical margin of error is 3–4 percentage points compared to laboratory methods such as DEXA. This means a result of 20% could reflect a true value of 16–24%. Use the result as a useful indicator of your general category, not as a precise measurement.
How to Take Accurate Measurements
Measurement technique significantly affects accuracy. Follow these guidelines for best results:
Use a flexible tape measure (cloth or plastic), not a rigid ruler. Measure directly on skin, not over clothing.
Waist: Measure horizontally at the level of your navel (belly button), while relaxed — do not suck in your stomach. Take the measurement at the end of a normal exhale.
Neck: Measure just below the larynx (Adam's apple), with the tape angled slightly downward at the front. Keep your head level.
Hips (women only): Measure at the widest point of your hips and buttocks, standing with your feet together.
Take each measurement twice and use the average. If the two readings differ by more than 0.5 cm, take a third and average the closest two.
Measure at the same time of day for consistency — ideally in the morning before eating.
💡 Tip: For tracking progress over time, consistency of technique matters more than absolute accuracy. Even if the number is slightly off, measuring the same way each time will reliably show whether your body fat is going up, down, or staying the same.
Body Fat vs BMI: What's the Difference?
BMI and body fat percentage are related but distinct measures. BMI is calculated from height and weight alone and cannot distinguish between fat and muscle. Body fat percentage directly estimates the proportion of your body that is fat tissue.
In practice, this means:
A muscular athlete may have a high BMI (classified as "overweight") but a very low body fat percentage — reflecting excellent health.
An older adult who has lost muscle may have a "normal" BMI but an elevated body fat percentage, representing a risk that BMI alone would miss.
For most healthy, non-athletic adults, BMI and body fat percentage tend to align reasonably well.
Using both measurements together gives a more complete picture of body composition than either alone.
How to Reduce Body Fat
Sustainable body fat reduction requires two things working together: a moderate calorie deficit and resistance training to preserve muscle mass.
Calorie deficit: A deficit of 300–500 calories per day below your maintenance level results in gradual fat loss without excessive muscle loss. Use the Calorie Calculator to find your starting point.
Protein intake: Aim for 1.6–2.2 g of protein per kg of bodyweight per day during a deficit. This protects muscle tissue while losing fat. See our high-protein foods guide for practical food choices.
Resistance training: Strength training 2–4 times per week sends a signal to preserve muscle during weight loss. Without it, a significant portion of weight lost comes from muscle, worsening body composition.
Cardiovascular exercise: Cardio increases overall calorie burn and improves cardiovascular health. HIIT (high-intensity interval training) has been shown to be particularly effective for reducing visceral fat. See our guide on best exercises to lose weight.
Sleep and stress: Poor sleep raises cortisol, which promotes fat storage, particularly around the abdomen. Prioritising 7–9 hours of sleep per night supports fat loss.
⚠️ Crash diets that severely restrict calories tend to cause muscle loss alongside fat loss, which can actually increase body fat percentage over time even as scale weight drops. Aim for slow, consistent progress.
References:
Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center Report, 1984.
American Council on Exercise. Body fat classifications. ACE Fitness.
Wilmore JH, et al. Body composition and body fat distribution in relation to health. Int J Obes Relat Metab Disord. 1996.