Body Fat % = 86.010 × log10(Waist − Neck) − 70.041 × log10(Height) + 36.76
US Navy Body Fat Calculator
Estimate body-fat percentage from height and tape measurements using the male or female US Navy circumference equation.
US Navy Body Fat Calculator
A US Navy Body Fat Calculator estimates body fat percentage from a small set of tape measurements. The method combines height with waist or abdomen and neck circumference for men, while the women’s equation also uses hip circumference.
The Navy circumference approach is useful when a measuring tape is available but specialist body-composition equipment is not. Its result is an estimate for general tracking—not a diagnosis or an exact clinical measurement.
Body Fat % = 163.205 × log10(Waist + Hip − Neck) − 97.684 × log10(Height) − 78.387
Estimate body fat with tape measurements
The interactive form is intentionally excluded from this standalone content page. Open the live page when you are ready to enter your measurements.
Open the live calculatorWhat Is a US Navy Body Fat Calculator?
This calculator applies a circumference-based body-fat equation rather than relying only on scale weight. It is often called the Navy tape method because the required inputs can be collected with a flexible measuring tape and a height measurement.
For a male estimate, the method normally uses height, neck, and waist or abdominal circumference. For a female estimate, it normally uses height, neck, waist, and hip circumference. The selected equation then produces an estimated body-fat percentage.
Uses common measurements
Height and a few circumference values replace the need for specialist scanning equipment.
Adds context beyond weight
The result estimates what portion of total body weight may be fat rather than reporting scale weight alone.
Compare repeated measurements
Using the same technique each time can make changes in the estimate easier to follow.
US Navy Body Fat Formula
The Navy method uses base-10 logarithms. Because the male and female equations use different combinations of measurements, the correct formula must be selected before calculating the estimate.
Body Fat % = 86.010 × log10(Waist − Neck) − 70.041 × log10(Height) + 36.76
Waist or abdomen circumference must be greater than neck circumference so that the logarithm uses a positive value.
Body Fat % = 163.205 × log10(Waist + Hip − Neck) − 97.684 × log10(Height) − 78.387
Hip circumference is required because it is part of the female equation’s combined circumference value.
Unit rule: These equations are commonly applied with inch values. When measurements are entered in centimeters, convert every value to inches before using the formula.
Centimeters and Inches
The live US Navy Body Fat Calculator accepts either centimeters or inches. Every measurement must use the same unit system.
Inches = Centimeters ÷ 2.54
Convert before calculating
Height, neck, waist, and hip measurements are divided by 2.54 before the inch-based equations are applied.
Use values directly
No conversion is required when every input has already been measured in inches.
Do not mix centimeters and inches in one calculation. A mixed unit set can produce a meaningless estimate even when each individual number looks reasonable.
How to Use This US Navy Body Fat Calculator
Select male or female
The choice determines which equation and measurement fields are required.
Choose centimeters or inches
Select one unit system and use it consistently for height and every circumference measurement.
Enter height and neck circumference
Measure standing height without shoes and record neck circumference with the tape level and snug.
Add waist or abdominal circumference
Stand naturally and measure without pulling the stomach inward or compressing the skin.
Add hip circumference when required
The female equation uses the widest hip circumference in addition to height, neck, and waist.
Review the estimate
The live calculator applies the appropriate logarithmic equation and displays an estimated body-fat percentage.
The result is intended for general education and progress tracking. It should not replace medical assessment or individualized advice from a qualified healthcare professional.
How to Measure Correctly
Small differences in tape placement and tension can change the result. Use the same landmarks and technique whenever you repeat the calculation.
Stand straight without shoes
Keep feet flat, look forward, and record full standing height.
Keep the tape level
Measure around the neck while standing relaxed. The tape should touch the skin without digging in.
Use a consistent location
Measure the required waist or abdominal point while breathing normally. Do not flex or draw in the stomach.
Measure the widest point
For the female equation, circle the widest part of the hips while keeping the tape horizontal.
Worked Examples
Male measurement estimate
Height is 70 in, waist is 36 in, and neck is 16 in.
Waist − Neck = 36 − 16 = 20
86.010 × log10(20) − 70.041 × log10(70) + 36.76 ≈ 19.4%
86.010 × log10(20) − 70.041 × log10(70) + 36.76 ≈ 19.4%
The estimated body-fat percentage is approximately 19.4%.
Female measurement estimate
Height is 64 in, waist is 30 in, hip is 40 in, and neck is 13 in.
Waist + Hip − Neck = 30 + 40 − 13 = 57
163.205 × log10(57) − 97.684 × log10(64) − 78.387 ≈ 31.7%
163.205 × log10(57) − 97.684 × log10(64) − 78.387 ≈ 31.7%
The estimated body-fat percentage is approximately 31.7%.
Convert centimeters first
A male user records height 175 cm, waist 90 cm, and neck 40 cm.
175 ÷ 2.54 = 68.90 in
90 ÷ 2.54 = 35.43 in
40 ÷ 2.54 = 15.75 in
90 ÷ 2.54 = 35.43 in
40 ÷ 2.54 = 15.75 in
After conversion, the male Navy equation can be applied to the inch values.
Estimate fat and lean mass
A person weighs 180 lb and receives an estimated Navy body-fat result of 22%.
Fat Mass = 180 × 22 ÷ 100 = 39.6 lb
Lean Body Mass = 180 − 39.6 = 140.4 lb
Lean Body Mass = 180 − 39.6 = 140.4 lb
US Navy Body Fat Calculator for Men
The male equation combines height with the difference between waist or abdomen and neck circumference.
log10(Waist − Neck)
A larger waist measurement generally raises the estimate, while neck circumference and height adjust the equation. Because the calculation uses waist minus neck, the waist value must be greater than the neck value.
Height
Use full standing height in the selected unit.
Waist or abdomen
Use the measurement location specified by the calculator method.
Neck
Measure with the tape level and the body relaxed.
US Navy Body Fat Calculator for Women
The female equation includes hip circumference as well as height, waist, and neck measurements.
log10(Waist + Hip − Neck)
Hip circumference should be measured at the widest point. Using the same landmarks and tape tension each time improves consistency when the calculation is repeated.
Height and neck
These measurements help relate the combined circumference value to overall body size.
Waist and hip
Both measurements are required in the female circumference equation.
US Navy Body Fat vs BMI
The Navy method and BMI describe different things. BMI relates weight to height, while the Navy method estimates body-fat percentage from height and circumference measurements.
| Measurement | Inputs | What It Indicates | Main Limitation |
|---|---|---|---|
| US Navy body fat | Height, waist, neck, and hip when required | Estimated percentage of body weight that may be fat | Highly sensitive to tape placement and measurement technique |
| BMI | Weight and height | Body size relative to height | Does not directly separate fat mass from muscle or other lean tissue |
| Scale weight | Total body weight | Current weight at the time of measurement | Does not describe body composition |
A muscular person can have a comparatively high BMI while maintaining a lower body-fat percentage. Reviewing multiple indicators can therefore provide better context than relying on one number.
US Navy Body Fat vs Fat Mass
Body-fat percentage is a proportion. Fat mass is the estimated amount of body weight represented by fat.
Fat Mass = Body Weight × (Body Fat Percentage ÷ 100)
For 180 lb at 22% body fat, estimated fat mass is 180 × 0.22 = 39.6 lb.
Lean Body Mass = Body Weight − Fat Mass
For 180 lb with 39.6 lb of estimated fat mass, estimated lean body mass is 140.4 lb.
Applications of the US Navy Body Fat Calculator
Review composition trends
Compare repeated estimates during strength training, weight management, or changes in activity.
Understand circumference methods
See how height and body circumferences combine in a Navy-style logarithmic equation.
Use accessible equipment
A flexible measuring tape makes the method practical when scans or specialist tools are unavailable.
Add another progress measure
Coaches may record consistent tape estimates alongside training performance and other indicators.
Look beyond scale changes
Body weight can remain similar even when estimated fat and lean mass change.
Compare one method over time
Use the same calculation method rather than mixing values from unrelated devices and formulas.
Accuracy of the US Navy Body Fat Calculator
This method gives an estimate rather than an exact measurement. Results can be affected by body shape, posture, muscle mass, hydration, tape position, tape tension, rounding, and unit conversion.
| Method | Typical Setting | Practical Consideration |
|---|---|---|
| Navy tape method | Home, fitness, or circumference checks | Easy to repeat, but technique can noticeably change the result |
| Skinfold calipers | Fitness assessment | Accuracy depends on site selection and tester skill |
| Bioelectrical impedance | Smart scale or gym equipment | Hydration and recent exercise can influence readings |
| DEXA scan | Professional body-composition assessment | Provides more detail but may cost more and require access to a facility |
Best use: Repeat the same measurement routine and focus on the direction of change rather than treating one result as perfectly precise.
Tips for Accurate Navy Body Fat Measurements
Use one unit system for every input.
Keep the tape horizontal around the body.
Make the tape snug without compressing the skin.
Stand naturally instead of flexing or drawing in the stomach.
Use the same measurement landmarks each time.
Repeat measurements and review unusually different values.
Measure under similar conditions when tracking progress.
Compare trends from the same method rather than unrelated tools.
Record the raw circumference values with the final percentage.
Common Mistakes When Using the Navy Method
Mixing centimeters and inches
All inputs must use the same unit or be converted consistently before the formula is applied.
Changing the waist location
Measuring a different point on each occasion can create an apparent change that is only a technique difference.
Pulling the tape too tightly
Compressing the skin can reduce the recorded circumference and alter the estimate.
Leaving out hip circumference
The female equation requires hip measurement in addition to height, neck, and waist.
Comparing unrelated methods as identical
Navy formulas, impedance scales, calipers, and scans can produce different values.
Treating an estimate as a diagnosis
The result is a practical calculation and should not be used to make medical decisions without professional guidance.
Frequently Asked Questions
What is a US Navy Body Fat Calculator?
It estimates body-fat percentage from height and circumference measurements using separate Navy-style equations for men and women.
How does the Navy body-fat formula work?
It combines height with waist, neck, and—when required—hip circumference in a base-10 logarithmic equation.
What is the male Navy body-fat formula?
Body Fat % = 86.010 × log10(Waist − Neck) − 70.041 × log10(Height) + 36.76.
What is the female Navy body-fat formula?
Body Fat % = 163.205 × log10(Waist + Hip − Neck) − 97.684 × log10(Height) − 78.387.
Can centimeters be used?
Yes. Convert every centimeter measurement to inches by dividing by 2.54 before applying the inch-based equations.
Does the main formula require body weight?
No. Height and circumference measurements are used for the percentage estimate. Body weight is needed only when calculating estimated fat mass or lean body mass.
Is Navy body fat more useful than BMI?
They provide different information. BMI relates weight to height, while the Navy method estimates body-fat percentage from measurements. Both have limitations.
How accurate is the estimate?
It is useful for general trend tracking, but tape position, body shape, and measurement technique can affect the result.
Can fat mass be calculated from the result?
Yes. Multiply body weight by body-fat percentage divided by 100 to estimate fat mass.
Is this medical advice?
No. The page provides general educational estimates and does not replace assessment or advice from a qualified healthcare professional.
Related Calculators
Body Fat Percentage Calculator
Estimate body composition and review fat-mass formulas.
Weight Loss Percentage Calculator
Compare current body weight with a starting weight.
Lean Body Mass Percentage Calculator
Estimate the share of body weight represented by lean mass.
Waist-to-Height Ratio Calculator
Compare waist circumference with total height.
Waist to Hip Ratio Calculator
Compare waist circumference with hip circumference.
Percentage Change Calculator
Measure relative change between an earlier and later value.
Final Note
A US Navy Body Fat Calculator provides a practical body-composition estimate from measurements that can be collected at home. The method is most useful when the same unit, landmarks, posture, and tape tension are used every time.
Because the output is an estimate, do not use it as a diagnosis or as the sole basis for health decisions. Seek qualified medical or fitness guidance when interpretation affects your wellbeing.
Ready to estimate your body-fat percentage?
Open the live page and enter all measurements using one consistent unit.
Use the US Navy Body Fat Calculator