Body Fat Percentage Calculator
Estimate your body fat percentage based on BMI, age, and sex.
What Is Body Fat Percentage?
Body fat percentage is the proportion of fat mass to total body mass. Direct methods try to estimate that split; this page does not. It estimates a percentage from BMI, age, and sex only. Two people with the same BMI can still differ in muscle, fat distribution, and health.
How to Use the Body Fat Calculator
- Enter your age — Type your current age in years.
- Select your sex — Choose Male or Female from the dropdown.
- Enter your BMI — Type your Body Mass Index (use our BMI Calculator if needed).
- Click "Calculate Body Fat" — The tool shows an estimated body fat percentage.
How Body Fat Is Estimated
This calculator uses the Deurenberg formula, a widely used estimation equation based on BMI, age, and sex:
- Male: Body Fat % = 1.20 × BMI + 0.23 × Age − 16.2
- Female: Body Fat % = 1.20 × BMI + 0.23 × Age − 5.4
This calculator estimates body fat percentage from BMI, age, and sex. It does not directly measure fat tissue. Results can differ for athletes and people with high muscle mass, and they should be treated as a range, not a lab value.
Body Fat Categories
| Category | Men | Women |
|---|---|---|
| Essential Fat | 2–5% | 10–13% |
| Athletic | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Note: The table is a common population reference. The gauge is an illustrative 2–50% scale and does not diagnose health status or classify fitness. This calculator does not assign you a row in the table.
Why Body Fat Percentage Matters
- Context, not a diagnosis: Measured body fat can add context beyond weight, but this calculator only estimates from BMI, age, and sex.
- Tracking: Repeating the same method over time is more useful than treating a single estimate as a verdict.
- Not a body-composition scan: This tool cannot tell whether weight is muscle or fat.
- Not a goal prescription: It does not set a personal target or diet plan.
Limitations of This Calculator
- Not accurate for athletes — high muscle mass inflates BMI, which inflates estimated body fat.
- Doesn't work for children or pregnant women — they need separate reference charts.
- Population-based estimate — other methods (DEXA, hydrostatic weighing, skinfolds) assess composition differently and still have limits.
- Doesn't account for ethnicity — body composition norms differ across populations.
Frequently Asked Questions
What is a healthy body fat percentage?
There is no single “healthy” percentage for everyone. Published ranges vary by age and sex and are population references, not a diagnosis from this calculator. Very low estimated values are not a goal this page recommends; discuss unusual results with a clinician.
How accurate is this body fat calculator?
This calculator estimates body fat percentage from BMI, age, and sex. It does not directly measure fat tissue. Estimates can be off for athletes, older adults, or people with high muscle mass. Other methods such as DEXA or hydrostatic weighing are different assessments, not a guarantee of a “true” number.
Why does body fat percentage vary by age?
The Deurenberg estimate includes age because, at a given BMI, older adults often have a higher estimated fat percentage in population studies. That is a statistical pattern, not a measurement of your muscle or fat.
Can I use this calculator for fitness goals?
You can repeat the same BMI, age, and sex estimate over time as one data point. It is not a personalized training plan or a direct reading of body composition. Weight, how clothes fit, and clinical advice still matter more than a single percentage.
What's the difference between body fat and BMI?
BMI is a ratio of weight to height. This calculator then estimates a body-fat percentage from that BMI plus age and sex. It does not directly measure fat tissue. Two people with the same BMI can still differ in muscle and fat; this tool cannot show that difference.
Does this calculator tell me how to lower body fat?
No. It does not provide a diet or training plan. It only estimates a percentage from BMI, age, and sex.