Body Fat Percentage Calculator

Body Fat Percentage Categories

U.S. Army Body Fat Standards

FFMI Interpretation Guide

Fat-Free Mass Index (FFMI) measures muscle mass relative to height. Use this table to interpret your FFMI results.

Note: These ranges apply primarily to men. Women naturally have lower FFMI values; an FFMI of 18-20 would be considered excellent for most women.

Recommended Body Fat Ranges by Goal

Your ideal body fat percentage depends on your specific goals. Use this table as a general guide.

Calculation Formulas

This calculator uses validated formulas developed by the U.S. Navy. Below are the exact calculations performed for each measurement.

Navy Body Fat Formula (Men)

Variables:

• waist: Waist circumference in inches, measured at the navel
• neck: Neck circumference in inches, measured at the narrowest point
• height: Total height in inches

Navy Body Fat Formula (Women)

Variables:

• waist: Waist circumference in inches, measured at the navel
• hip: Hip circumference in inches, measured at the widest point
• neck: Neck circumference in inches, measured at the narrowest point
• height: Total height in inches

FFMI Formula

Variables:

• Lean Mass: Weight × (1 − Body Fat % ÷ 100), converted to kilograms
• Height: Height converted to meters
• 6.1 and 1.8: Adjustment constants for height normalization (1.8m = 5'11")

Worked Example: Male Calculation

For a male with height 5'10" (70"), neck 15", waist 34":

Understanding Your Results

Knowing your body fat percentage is only useful if you understand what it means and what actions to take based on different results.

What the Numbers Mean

Body fat percentage tells you what portion of your total body weight is fat tissue. The remainder is lean mass—muscle, bone, organs, water, and other non-fat tissue. A 180 lb person at 20% body fat has 36 lbs of fat and 144 lbs of lean mass.

Fat mass vs. lean mass helps you understand body composition changes. If you lose 10 lbs total but only 5 lbs of fat mass, you also lost 5 lbs of muscle—which isn't ideal. Tracking both numbers helps ensure you're losing fat, not muscle.

FFMI measures muscularity independent of fat. Two people can have the same body fat percentage but very different FFMI values if one has more total muscle mass.

When Should You Be Concerned?

Actions Based on Your Results

If you're in the Obese category:

• Focus on sustainable calorie reduction (300-500 calories below maintenance)
• Include resistance training to preserve muscle while losing fat
• Aim to lose 0.5-1% body fat per month
• Consider consulting a healthcare provider for personalized guidance

If you're in the Average category:

• You're in an acceptable range for general health
• To improve, add structured exercise (both cardio and strength training)
• Minor nutrition adjustments can move you toward Fitness category
• Focus on body recomposition rather than just weight loss

If you're in the Fitness category:

• You've achieved a healthy, sustainable body composition
• Focus on maintaining current habits
• Further fat loss toward Athlete levels requires more strict adherence
• Consider whether the effort required for lower body fat is worth it for your goals

If you're in the Athlete/Essential category:

• Ensure you're eating enough to support health and performance
• Monitor for signs of underfueling (fatigue, frequent illness, poor recovery)
• Women should watch for menstrual irregularities
• Very low body fat may not be sustainable or necessary outside of competition

Body Fat Measurement Methods Compared

The Navy/Army tape method is one of several ways to measure body fat. Here's how it compares to other common methods.

Why use the Navy method? It offers a good balance of accuracy and accessibility. While not as precise as DEXA or hydrostatic weighing, it's free, can be done at home, and is accurate enough to track trends over time. The method has been validated through decades of military use and correlates well with more expensive measurement techniques.

When to consider other methods: If you need highly accurate baseline measurements for medical reasons, or if tape measurements seem inconsistent with your visual appearance, a DEXA scan can provide definitive numbers and show where fat is distributed in your body.

How to Use This Calculator

This calculator offers four different tools for assessing body composition. Each tab serves a specific purpose and requires different inputs. Here's how to get the most accurate results from each method.

Navy Method Tab

The Navy Method estimates body fat percentage using circumference measurements. This is the most comprehensive body fat calculation available on this site.

Required inputs:

• Gender: Select male or female. The formulas differ significantly because men and women store fat differently.
• Height: Enter your height in feet and inches. Measure without shoes, standing straight against a wall.
• Weight: Enter your current weight in pounds. Weigh yourself in the morning, after using the bathroom, before eating.
• Neck: Measure at the narrowest point, just below your Adam's apple (larynx). Keep the tape horizontal.
• Waist: Measure at your navel (belly button) level. Keep the tape horizontal, don't suck in your stomach, and measure at the end of a normal breath.
• Hip (women only): Measure at the widest point of your hips and buttocks. This measurement is only used in the female formula.

Understanding your results: You'll receive your body fat percentage, fat mass in pounds, lean mass in pounds, and a category classification (Essential, Athlete, Fitness, Average, or Obese). The visual chart shows where you fall on the body fat spectrum.

Army Test Tab

The Army Test uses the same body fat calculation as the Navy Method but compares your result against official U.S. Army body composition standards.

Additional input:

• Age: Enter your current age. Army limits vary by age group: 17-20, 21-27, 28-39, and 40+.

Understanding your results: You'll see your body fat percentage, the maximum allowed for your age group and gender, the difference from the limit, and a clear PASS or FAIL indicator. This is useful for military personnel, applicants, or anyone curious about meeting military fitness standards.

FFMI Tab

The FFMI (Fat-Free Mass Index) Calculator measures your muscle mass relative to your height. Unlike body fat percentage, FFMI focuses on how much lean tissue you carry.

Required inputs:

• Weight: Your current weight in pounds.
• Height: Your height in feet and inches.
• Body Fat %: Your current body fat percentage. You can use the Navy Method tab first to calculate this, then enter it here.

Understanding your results: You'll receive your FFMI score, a height-normalized FFMI (which adjusts for different heights), and your lean mass in pounds. An FFMI under 18 is below average, 18-20 is average, 20-22 is above average, 22-25 is excellent/near the natural limit, and above 25 is typically only achievable with performance-enhancing substances or exceptional genetics.

BF Chart Tab

The Body Fat Chart is a simple reference tool for looking up what category a given body fat percentage falls into.

Required inputs:

• Gender: Categories differ between men and women.
• Body Fat %: Enter any body fat percentage to see its classification.

Understanding your results: You'll see the category name and a visual representation of where that percentage falls on the scale. The table shows all category ranges for quick reference.

Tips for Accurate Measurements

• Use a flexible measuring tape: Cloth or plastic tape measures work best. Don't use metal tapes.
• Measure consistently: Take measurements at the same time of day, ideally in the morning.
• Don't compress: The tape should be snug but not tight enough to indent your skin.
• Take multiple readings: Measure 2-3 times and use the average for more accuracy.
• Stand naturally: Don't suck in your stomach or flex muscles while measuring.
• Measure on skin: Remove clothing or measure over very thin fabric for best results.

Common Mistakes to Avoid

• Measuring waist at the wrong spot: The Navy method requires measurement at the navel, not the narrowest part of your waist.
• Holding your breath: Breathe normally and measure at the end of a regular exhale.
• Measuring after eating: Food and water can temporarily increase waist circumference.
• Using old body fat numbers for FFMI: If your weight has changed, recalculate your body fat percentage first.
• Comparing results from different times of day: Body measurements can vary by up to an inch throughout the day due to hydration, food intake, and activity.

Real-World Examples

These examples show how different people might use this calculator and what their results would mean. All calculations use the actual formulas from this calculator.

Example 1: Mike – Competitive Triathlete

Mike is a 28-year-old male who competes in triathlons. He wants to track his body composition during training season.

His measurements: Height 5'10", Weight 175 lbs, Neck 15.5", Waist 34"

Navy Method results: Body fat 10.1%, Fat mass 17.7 lbs, Lean mass 157.3 lbs

What this means: Mike falls in the Athlete category (6-13% for men). His low body fat helps with endurance performance, and his lean mass of 157 lbs provides the muscle needed for swimming, cycling, and running. This is a healthy range for a competitive endurance athlete.

Example 2: David – Office Professional

David is a 42-year-old male who works a desk job. He's concerned about his health after his annual checkup and wants to understand his body composition.

His measurements: Height 5'9", Weight 195 lbs, Neck 16", Waist 40"

Navy Method results: Body fat 19.9%, Fat mass 38.9 lbs, Lean mass 156.1 lbs

What this means: David is in the Average category (18-24% for men). He's not in the obese range, but reducing body fat to the Fitness range (14-17%) would improve his health markers. He carries about 39 lbs of fat—losing 10-15 lbs of fat while maintaining muscle would put him in the Fitness category.

Example 3: Sarah – Marathon Runner

Sarah is a 32-year-old female training for her third marathon. She wants to ensure she's maintaining adequate body fat for training while staying lean for performance.

Her measurements: Height 5'6", Weight 135 lbs, Neck 12.5", Waist 31", Hip 40"

Navy Method results: Body fat 8.6%, Fat mass 11.6 lbs, Lean mass 123.4 lbs

What this means: Sarah is in the Essential Fat category (10-13% for women). While some female endurance athletes operate at this level, it's at the lower edge of healthy. She should monitor for signs of relative energy deficiency in sport (RED-S), such as missed periods or increased injuries. Slightly higher body fat (14-18%) might be healthier for long-term training.

Example 4: Lisa – Starting a Fitness Journey

Lisa is a 38-year-old female who recently started exercising. She wants a baseline measurement to track progress over the coming months.

Her measurements: Height 5'4", Weight 170 lbs, Neck 13", Waist 39", Hip 46"

Navy Method results: Body fat 23.8%, Fat mass 40.4 lbs, Lean mass 129.6 lbs

What this means: Lisa is in the Fitness category (21-24% for women), which is a healthy range. As she continues exercising, she can use monthly measurements to track changes. Her goal might be to maintain lean mass while reducing fat mass slightly, or to increase muscle while keeping fat stable.

Example 5: James – Army Reservist

James is a 35-year-old male Army Reservist preparing for his annual fitness assessment. He needs to know if he'll pass the body composition portion of the test.

His measurements: Height 5'11", Weight 190 lbs, Age 35, Neck 15.5", Waist 37"

Army Test results: Body fat 15.1%, Army limit for age 28-39: 24%, Difference: -8.9%

What this means: James passes the Army body composition standard by a comfortable margin. He's 8.9 percentage points under the maximum allowed for his age group. Even if his measurements vary slightly on test day, he has significant room before approaching the limit.

Example 6: Rachel – Army ROTC Cadet

Rachel is a 21-year-old female ROTC cadet who will commission next year. She wants to ensure she meets body composition standards for active duty.

Her measurements: Height 5'6", Weight 155 lbs, Age 21, Neck 13", Waist 34", Hip 42"

Army Test results: Body fat 13.5%, Army limit for age 21-27: 32%, Difference: -18.5%

What this means: Rachel easily passes Army standards. Her body fat is well below the 32% maximum for women in her age group. She's actually in the Athlete category for general body fat classifications.

Example 7: Chris – Experienced Weightlifter

Chris is a 30-year-old male who has been lifting weights seriously for eight years. He wants to know how his muscle development compares to natural limits.

His measurements: Height 5'10", Weight 195 lbs, Body fat 12%

FFMI results: FFMI 24.6, Normalized FFMI 24.8, Lean mass 171.6 lbs

What this means: Chris has an Excellent FFMI that's approaching the natural limit of about 25. This indicates eight years of consistent training has produced near-maximum natural muscle development. Gaining additional lean mass from here will be very slow and difficult without pharmaceutical assistance. His focus should be on maintaining this level while optimizing body fat for his goals.

Example 8: Tom – Fitness Enthusiast

Tom is a 45-year-old male who exercises regularly but isn't a competitive athlete. He wants to understand his current body composition status.

His measurements: Height 5'10", Weight 180 lbs, Neck 15", Waist 37"

Navy Method results: Body fat 16.3%, Fat mass 29.4 lbs, Lean mass 150.6 lbs

What this means: Tom is in the Fitness category (14-17% for men), which is excellent for his age. He's leaner than average while maintaining good muscle mass. This body composition supports both health and physical performance for recreational activities.

Example 9: Robert – Health-Conscious Retiree

Robert is a 55-year-old male who recently retired and wants to focus on health. His doctor suggested tracking body composition alongside weight.

His measurements: Height 5'8", Weight 205 lbs, Neck 17", Waist 42"

Navy Method results: Body fat 21.9%, Fat mass 44.9 lbs, Lean mass 160.1 lbs

Army Test results (if applicable): Army limit for 40+: 26%, Difference: -4.1% (passes)

What this means: Robert is in the Average category (18-24% for men). While not ideal, he's not in the obese range and would pass Army standards for his age if they applied. A reasonable goal would be reaching the Fitness category (14-17%) through a combination of strength training to maintain lean mass and modest calorie reduction to lose fat.

Example 10: Maria – New Gym Member

Maria is a 29-year-old female who just joined a gym and wants to set realistic body composition goals.

Her measurements: Height 5'5", Weight 160 lbs, Neck 13", Waist 37", Hip 45"

Navy Method results: Body fat 20.2%, Fat mass 32.3 lbs, Lean mass 127.7 lbs

What this means: Maria is at the top of the Athlete category (14-20% for women), which is already a healthy range. Her initial focus should be on building strength and maintaining this body fat level rather than aggressive fat loss. Adding muscle through resistance training will improve her body composition even if the scale doesn't change much.

When to Use This Calculator

Body fat percentage provides more insight than weight alone. Here are specific situations where this calculator is most valuable:

1. Starting a Fitness or Weight Loss Program

Before beginning any fitness program, establish your baseline body composition. This lets you track whether you're losing fat, gaining muscle, or both. The scale might not move, but your body fat percentage can improve significantly as you replace fat with muscle tissue.

2. Military Fitness Assessments

If you're in the military, applying to join, or in ROTC, use the Army Test tab to check if you meet body composition standards. The Army uses a tape test for soldiers who exceed height/weight screening limits. Knowing your numbers beforehand helps you prepare and identify how much margin you have.

3. Tracking Progress Over Time

Take measurements monthly to monitor changes. Body fat percentage is a better progress indicator than weight because it distinguishes between fat loss and muscle loss. Someone losing 10 lbs of fat while gaining 5 lbs of muscle has dramatically improved their body composition, even though they only lost 5 lbs total.

4. Setting Realistic Fitness Goals

Understanding your current category helps set achievable targets. Moving from Average to Fitness is realistic in 3-6 months. Going from Fitness to Athlete may take a year or more of dedicated training and nutrition. Knowing where you start helps you plan appropriately.

5. Evaluating Muscle Development

The FFMI calculator helps experienced lifters understand their muscle development relative to natural limits. If your FFMI is already above 22-23, further muscle gains will be slow and challenging. If it's below 20, you have significant natural potential remaining.

6. Health Risk Assessment

Body fat percentage correlates with various health risks more closely than BMI. Men above 25% and women above 32% face increased risks for type 2 diabetes, heart disease, and metabolic syndrome. This calculator helps identify if your body composition puts you in a higher-risk category.

7. Athletic Performance Optimization

Athletes in weight-class sports, endurance events, or aesthetic sports need to balance low body fat with sufficient energy and health. This calculator helps determine if you're in an appropriate range for your sport or if further fat loss might compromise performance or health.

8. Post-Injury or Illness Recovery

After periods of inactivity, body composition often shifts—you may lose muscle and gain fat even if weight stays stable. Measuring body fat helps track recovery and ensures you're rebuilding muscle, not just returning to your previous weight.

Who Benefits Most From This Tool

• Fitness beginners who need a starting point and way to track progress
• Military personnel who must meet body composition standards
• Athletes optimizing body composition for performance
• People losing weight who want to ensure they're losing fat, not muscle
• Weightlifters curious about their muscle development compared to natural limits
• Anyone interested in health who wants more insight than a scale provides

Related Guides

Dive deeper into body composition topics with our comprehensive guides.

Master Body Composition

Understanding body fat percentage is just the beginning. Our in-depth guides cover everything from the science of body composition to practical advice for achieving your goals.

• What's a Healthy Body Fat Percentage? – Learn the optimal ranges for different goals, ages, and activity levels.
• Body Fat Percentage for Men – Male-specific ranges, what different percentages look like, and how testosterone affects body composition.
• Body Fat Percentage for Women – Female-specific considerations, healthy ranges, and how hormones influence where fat is stored.
• Visual Body Fat Percentage Chart – See what different body fat levels look like with our visual reference guide.

Browse all guides →

Frequently Asked Questions