Body Fat Percentage Calculator
Estimate body fat percentage using the US Navy circumference method · free, no signup
How Body Fat Percentage Calculator works, step by step
Measure your height, neck and waist (and hips if female) with a tape measure.
Download itEnter the measurements and your sex.
Free Body Fat Percentage Calculator (Navy Method)
Body Mass Index does not distinguish between fat and muscle, which is why the US Navy developed a circumference-based method that estimates body fat percentage from a few tape-measure readings: height, neck and waist for men, plus hip for women. This calculator applies that formula and shows both the estimated body fat percentage and which category it falls into, from essential fat through athletic, fitness, average and obese ranges.
It is not as accurate as clinical methods like DEXA scans or hydrostatic weighing, but it is a free, private and reasonably reliable way to track trends over time using nothing more than a tape measure. Take the same measurements the same way each time for the most meaningful comparisons.
Key features
US Navy formula
The circumference method used in military fitness testing.
Category result
Essential fat, athletic, fitness, average or obese range.
Metric or imperial
Enter measurements in cm/kg or inches/pounds.
Private and instant
Nothing is uploaded; the result appears as you type.
How to use it
- Measure your height, neck and waist (and hips if female) with a tape measure.
- Enter the measurements and your sex.
- Read your estimated body fat percentage.
- Track it again in a few weeks using the same technique to see the trend.
Worked example
Example
Male, height 178cm, neck 38cm, waist 86cm → estimated body fat ≈ 16.8%, in the 'fitness' category.
Who uses this tool
Anyone tracking fitness progress
A free way to estimate body composition without special equipment.
Gym-goers and athletes
Track body fat trends alongside weight and BMI.
Anyone starting a fitness plan
Get a starting-point estimate before a program begins.
Tips for the best results
- Measure at the same time of day and in the same way each time for consistent results.
- Keep the tape snug but not compressing the skin, and measure at the same body landmarks each time.
- Use the trend over weeks and months rather than a single reading, which can vary a percent or two.
- Combine with other measures like waist circumference and how clothes fit, not this number alone.
Common mistakes to avoid
- Measuring over clothing, which adds inches and skews the result.
- Comparing a single reading to someone else's instead of tracking your own trend.
- Treating the estimate as clinically precise — it is a useful estimate, not a diagnostic measurement.
Why use AZRS QuickFix?
It is 100% free, needs no signup and has no watermark or usage limits. The tool runs in your browser, so what you type stays on your device, and it works on phones, tablets and desktops. New tools are added every week — bookmark this page or browse the full QuickFix toolbox.
Frequently asked questions
How accurate is the Navy method?
It is generally within a few percentage points of more precise methods like DEXA for most people, making it useful for tracking trends rather than an exact clinical reading.
What is a healthy body fat percentage?
Roughly 10–20% for men and 18–28% for women is often cited as a healthy range, though it varies with age and goals.
Do I need special equipment?
Just a flexible tape measure and a way to measure your height.
Why does the formula need hip measurement for women but not men?
Body fat distribution differs by sex, and the Navy formula's regression was developed separately for men and women to improve accuracy.
Is this the same as BMI?
No. BMI only uses height and weight; this method estimates actual body composition from circumference measurements.
Is my data stored?
No, everything calculates locally and nothing is saved or sent anywhere.