RFM Body Fat Calculator
Estimate your body fat percentage using height and waist measurements.
Quick Guide & Tips
How to Use the Calculator
Select your sex, choose metric or imperial units, and enter your waist circumference and height.
Measure your waist using a flexible tape, keeping it snug but not tight, and stand in a relaxed, upright position.
After entering your measurements, click “Calculate” to see your estimated body fat percentage.
Tips for Interpreting Your Results
Body fat percentage focuses on how much of your body weight comes from fat tissue, offering a different perspective than weight or BMI alone.
Results should be viewed as a general reference, as factors such as age, muscle mass, activity level, and genetics can influence body composition.
Use your result as a starting point to better understand your body rather than as a definitive assessment of health.
Tracking Progress Over Time
Repeating body fat calculations periodically can help you observe trends and evaluate the impact of lifestyle changes.
Daily fluctuations are normal, so focus on longer-term patterns instead of individual measurements.
Consistent tracking can support goal setting related to fitness, nutrition, and overall wellness.
Lifestyle and Wellness Considerations
Body composition is influenced by a combination of physical activity, nutrition, sleep, and stress management.
Regular movement, balanced meals, and strength-building activities can all play a role in maintaining healthy body fat levels.
Gradual, sustainable habit changes are often more effective than short-term or extreme approaches.
Frequently Asked Questions
What is the RFM Body Fat formula?
The Relative Fat Mass (RFM) formula estimates body fat percentage using waist circumference and height, with sex-specific calculations. It provides a simple, practical method to assess body fat composition without special equipment.
What are the Body Fat categories?
Body fat percentages are classified into categories that indicate general health ranges. While these ranges can vary slightly by source, a commonly used classification is:
Men:
- Very low fat: Less than 2%
- Essential fat: 2 – 5.9%
- Athletes: 6 – 13.9%
- Fitness: 14 – 17.9%
- Average: 18 – 24.9%
- Obese: 25% and above
Women:
- Very low fat: Less than 10%
- Essential fat: 10 – 13.9%
- Athletes: 14 – 20.9%
- Fitness: 21 – 24.9%
- Average: 25 – 31.9%
- Obese: 32% and above
These categories provide a guideline for interpreting results and planning fitness or health goals. Individual health assessment should consider other factors like age, lifestyle, and muscle mass.
Is Body Fat RFM Formula accurate?
The RFM formula provides reliable estimates for most adults and is especially useful for the general population. While it may be less precise for very muscular or obese individuals, it performs well as a simple, accessible body fat estimation method.
How should I measure my waist?
Use a flexible measuring tape and measure your waist differently depending on sex:
For men: Measure at the level of the navel (belly button).
For women: Measure at the narrowest part of the torso, usually above the navel and below the rib cage.
Stand upright, relax your abdomen, and keep the tape snug but not tight.
What is the difference between BMI and body fat percentage?
BMI shows how heavy you are for your height, while body fat percentage shows how much of your body is fat.
BMI is a basic calculation based only on height and weight. It compares body weight to height, but it does not measure body fat. Because of this, muscular individuals may be classified as overweight, while people with lower muscle mass and higher fat levels may appear normal.
Body fat percentage focuses directly on body fat and provides a clearer picture of body composition. Methods such as the Navy and RFM formulas estimate body fat using body measurements like waist, neck, height, and sometimes hips.