💪 Health & Fitness

Body Fat Calculator

Estimate your body fat percentage using the US Navy method. Get your fat mass, lean mass, and fitness category — all you need is a tape measure.

💪 Calculate Your Body Fat Percentage

Enter your measurements below. Use a flexible tape measure for best accuracy.

Unit System

Sex

Height

Weight

Waist circumference

Neck circumference

📏 Measure waist at the narrowest point (navel level), neck just below the larynx, hips at the widest point (women only).

Body Fat %

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Fat Mass

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Lean Mass

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Estimate only. US Navy circumference method. Consult a healthcare professional for clinical assessment.

What Is a Body Fat Calculator?

This body fat calculator estimates your body fat percentage using the US Navy circumference method. It is one of the most practical body fat assessment tools available — all you need is a flexible tape measure. This body fat calculator gives you your body fat percentage, fat mass, lean mass, and fitness category without any expensive equipment or gym visit.

Body fat percentage is a more informative health metric than weight alone. In fact, two people of identical weight can have very different body compositions — and very different health risks. This body fat calculator reveals what the scale cannot.

How Does the Body Fat Calculator Work?

This body fat calculator uses the US Navy circumference formula, developed and validated by the US military for population-level body composition assessment.

Body Fat Calculator Formula for Men

BF% = 495 / (1.0324 − 0.19077×log10(waist−neck) + 0.15456×log10(height)) − 450

Body Fat Calculator Formula for Women

BF% = 495 / (1.29579 − 0.35004×log10(waist+hip−neck) + 0.22100×log10(height)) − 450

This body fat calculator applies these formulas automatically. All you need to do is enter your measurements and select your sex. The body fat calculator converts imperial measurements to metric internally if needed.

How to Measure for This Body Fat Calculator

Accurate measurements are essential for a reliable body fat calculator result. Here is how to measure correctly.

Height: Stand straight against a wall without shoes. Measure to the top of your head.
Waist: Measure at the narrowest point — typically at or just above the navel. Exhale normally before measuring. Do not suck in.
Neck: Measure just below the larynx (Adam’s apple), sloping slightly downward at the front.
Hips (women only): Measure at the widest point of the hips and buttocks.

💡 Take all measurements in the morning before eating or drinking. Use a flexible tape measure pulled snug but not compressing the skin. Take each measurement twice and use the average for the most consistent body fat calculator result.

What Does Your Body Fat Calculator Result Mean?

This body fat calculator classifies your result into standard fitness categories. The ranges differ for men and women.

Body Fat Categories for Men

2–5%: Essential fat. Minimum required for biological function. Seen in competitive bodybuilders.
6–13%: Athletic. Lean and defined. Typical of endurance athletes and serious gym-goers.
14–17%: Fitness. Above average. Healthy and fit appearance.
18–24%: Average. Typical for general population. Low visible muscle definition.
25%+: Obese range. Associated with elevated health risk.

Body Fat Categories for Women

10–13%: Essential fat. Women require more essential fat than men for hormonal and reproductive function.
14–20%: Athletic. Lean and defined. Typical of female athletes.
21–24%: Fitness. Healthy and toned appearance.
25–31%: Average. Healthy range for general population.
32%+: Obese range. Associated with elevated health risk.

Is This Body Fat Calculator Accurate?

The US Navy body fat calculator method has a margin of error of approximately 3–4% compared to DEXA scanning — the gold standard for body composition measurement. For most people, this level of accuracy is sufficient for tracking trends over time.

However, this body fat calculator tends to underestimate body fat in very lean individuals and overestimate in those with high central adiposity. According to research published in the Journal of Strength and Conditioning Research, the Navy method remains one of the most practical and accessible body fat assessment tools for general use.

⚠️ This body fat calculator is an estimate. It is not a clinical diagnostic tool. For precise body composition assessment, use DEXA scanning or hydrostatic weighing. Consult a healthcare professional if you have concerns about your body composition.

Body Fat Calculator for Women — Is It Accurate?

Yes — this body fat calculator uses a separate formula for women that includes hip measurement. Women naturally carry more body fat than men, particularly subcutaneous fat in the hips and thighs. This is biologically normal and the body fat calculator accounts for it through the sex-specific formula.

Furthermore, women’s body fat percentage can fluctuate slightly throughout the menstrual cycle due to water retention. Therefore, take measurements at the same point in your cycle each time for the most consistent body fat calculator comparisons.

Body Fat Calculator for Men — Is It Accurate?

Yes — this body fat calculator uses a validated formula for men that relies on waist and neck measurements. For men who carry significant fat centrally (around the abdomen), this body fat calculator is particularly accurate since waist circumference is the primary measurement.

However, for men with unusually large neck circumference due to muscle mass, the body fat calculator may slightly underestimate body fat percentage. In that case, supplement with a skinfold measurement or DEXA for a more complete picture.

Common Mistakes When Using a Body Fat Calculator

Measuring inconsistently: Always measure at the same time of day, in the same location, with the same tape tension. Small measurement differences create large body fat calculator variation.
Sucking in during waist measurement: The waist measurement should reflect your natural, relaxed circumference after a normal exhale. Sucking in underestimates your body fat calculator result.
Checking too frequently: Body fat changes slowly. Weekly or monthly checks are sufficient. Daily body fat calculator checks can cause anxiety due to normal fluctuation from hydration and food intake.
Using body fat calculator results as a sole health indicator: Body fat is one metric among many. Cardiovascular fitness, blood markers, and strength levels are equally important health indicators.

Body Fat Calculator — Frequently Asked Questions

What is a healthy body fat percentage according to this body fat calculator?

According to this body fat calculator and standard fitness guidelines, healthy body fat is approximately 10–20% for men and 18–28% for women. Athletes typically fall below these ranges. Values above 25% for men and 32% for women shown by the body fat calculator are associated with increased health risk.

How is this body fat calculator different from a BMI calculator?

A BMI calculator only considers height and weight — it cannot distinguish between muscle and fat. In contrast, this body fat calculator uses circumference measurements that better reflect actual body composition. A muscular person might be overweight by BMI but have a healthy body fat calculator result. Use both tools together for the most complete picture.

How often should I use this body fat calculator?

Monthly measurements are ideal for tracking progress. More frequent body fat calculator checks can show misleading fluctuations due to hydration, time of day, and measurement technique. Always measure under the same conditions for consistent body fat calculator comparisons over time.

Can I reduce body fat without losing weight?

Yes — this is called body recomposition. It involves losing fat while gaining muscle, so the scale may not change much. However, your body fat calculator result will improve. This is common in beginners to resistance training and in people returning to exercise after a break.

Is this body fat calculator free?

Yes — this body fat calculator is completely free. There is no registration, no account, and no limit on calculations. It runs entirely in your browser so your measurements are never sent to any server.