Free BMI + Body Fat Calculator
Enter your measurements below to estimate your Body Mass Index (BMI) and body fat percentage. This tool uses the U.S. Navy circumference method for body fat and standard BMI formula.
Tip: Use a soft measuring tape, keep it level, and do not pull it too tight.
What this calculator tells you
This page combines two useful health metrics in one place:
- BMI (Body Mass Index): A quick screening tool based on height and weight.
- Body Fat Percentage: An estimate of how much of your total body weight comes from fat tissue.
BMI is easy and fast, but it does not separate fat and muscle. Body fat percentage gives a more detailed picture of body composition. Using both together is usually more informative than using either one alone.
How BMI is calculated
The BMI formula is:
BMI = weight (kg) / [height (m)]²
BMI categories for adults are commonly interpreted as:
| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 - 24.9 | Normal weight |
| 25.0 - 29.9 | Overweight |
| 30.0 and above | Obesity |
Remember: muscular people can have a high BMI without having high body fat. That is why we also estimate body fat percentage.
How body fat percentage is estimated
This calculator uses the U.S. Navy circumference method, which estimates body fat from tape measurements:
- For men: height, neck, and waist
- For women: height, neck, waist, and hips
It is practical for home use and usually more meaningful than scale weight alone.
General body fat classification
| Men | Women | Interpretation |
|---|---|---|
| 2-5% | 10-13% | Essential fat |
| 6-13% | 14-20% | Athletes |
| 14-17% | 21-24% | Fitness range |
| 18-24% | 25-31% | Average |
| 25%+ | 32%+ | Higher body fat |
How to measure correctly
Waist
Measure around your abdomen at navel level, relaxed, after a normal exhale.
Neck
Measure just below the larynx with the tape slightly angled downward toward the front.
Hips (women)
Measure at the widest part of the hips/glutes while standing naturally.
How to use your results
Use these numbers as feedback, not labels. A smart approach:
- Track BMI and body fat once every 2-4 weeks.
- Combine with waist trend, strength performance, and energy levels.
- Aim for sustainable changes: nutrition quality, daily movement, resistance training, and sleep.
If your BMI and body fat are both high, focus on gradual fat loss while preserving muscle. If BMI is high but body fat is moderate, you may simply have more lean mass.
Limitations and medical disclaimer
No online calculator can replace individualized medical assessment. These values are estimates and can be affected by hydration, measurement error, age, ethnicity, and body type. If you have a medical condition, are pregnant, or need a targeted plan, speak with a physician or registered dietitian.