How to Calculate Body Fat (US Navy): A Step-by-Step Guide

Updated 5 Oct 2026 in Health & Fitness

Estimates body fat percentage from tape measurements.

Health numbers are most useful when you track them consistently. A quick calculation turns everyday measurements into something you can act on, whether that is planning meals, training for a run or preparing for a clinic visit.

What you need

• Sex
• Height (cm)
• Neck (cm)
• Waist (cm)
• Hip (cm, women only)

Step by step

1. Enter the sex.
2. Enter the height (cm).
3. Enter the neck (cm).
4. Enter the waist (cm).
5. Enter the hip (cm, women only).
6. The results update as you type, or press Calculate.
7. Read the body fat first, then the supporting figures below it.

The formula

US Navy circumference formula using log10 of waist, neck (and hip) and height.

Worked example

For example, with these inputs:

• Sex: Male
• Height (cm): 172
• Neck (cm): 38
• Waist (cm): 85
• Hip (cm, women only): 95

the calculator returns:

• Body fat: 17.45%

A second example

Now change the inputs to:

• Sex: Male
• Height (cm): 215
• Neck (cm): 38
• Waist (cm): 85
• Hip (cm, women only): 95

the calculator returns:

• Body fat: 10.93%

Practical tips

• Track trends over weeks rather than reacting to a single reading.
• Formulas give estimates for the average person; your doctor can account for your history and body composition.
• See a healthcare professional before big changes to diet or exercise, especially if you have a medical condition.
• Measure at the same time of day, ideally in the morning, for consistent readings.

Background

Research has shown that Asians tend to develop conditions such as type 2 diabetes and heart disease at lower body weights than Europeans. That is why the Health Promotion Board recommends lower BMI cut-offs for Singaporeans, with 23 marking the start of moderate risk.

Singapore's tropical climate means you lose more fluid through sweat, even when you are not exercising. Thirst, urine colour and how you feel are good guides, and needs rise during outdoor activity or heat waves.

Energy needs depend on age, sex, size and activity. Formulas such as Mifflin-St Jeor estimate resting needs, and an activity multiplier turns that into daily needs. Real requirements vary by a few hundred calories, so adjust based on how your weight changes over several weeks.

Related calculations

• Protein Intake Calculator: Estimates daily protein needs.
• Steps to Kilometres Calculator: Converts step counts (like your Healthy 365 tracker) to distance.
• Running Pace Calculator: Calculates pace for runs like the Standard Chartered Marathon or IPPT 2.4 km.
• Calories Burned Calculator: Estimates calories burned with MET values.

Want to skip the arithmetic? The free Body Fat Calculator (US Navy) does all of this instantly and updates as you type.

Run your own numbers: Body Fat Calculator (US Navy)