Body fat percentage is the share of your total weight that is fat, and it is a key indicator showing that two people at the same weight can be in very different states of health. A weight figure alone cannot tell muscle from fat, so it is easy to miss cases like "skinny fat" — a normal BMI but high body fat — or the reverse, where someone is muscular despite a high BMI. This calculator estimates body fat percentage from just your height, weight, age, and sex, without any measurement device like a body-composition scanner, and it also shows your fat mass (kg) and lean mass (muscle, bone, water, and so on).
The calculation uses the Deurenberg formula: body fat (%) = 1.2 × BMI + 0.23 × age − 10.8 × sex (male 1, female 0) − 5.4. It is based on research showing that BMI, age, and sex are strongly correlated with body fat percentage in statistical terms. That said, this approach is only an estimate built on population averages, so people with very high or very low muscle mass may see a gap from their real value. For that reason the result is shown as an "estimate," and an accurate figure requires a body-composition analyzer or a professional measurement. All calculations run entirely in your browser.
How to Use
- 1
Choose your sex
Select male or female. The normal body fat range differs substantially by sex.
- 2
Enter age, height, and weight
Enter your age (years), height (cm), and weight (kg). BMI is calculated first from these values.
- 3
Check the result
Along with the estimated body fat percentage, you will see your fat mass and lean mass, and which sex-specific reference band you fall into.
- 4
Copy the result
Use the copy button to save the result as text.
When It's Useful
A quick gauge without a body scan
When a body-composition device is hard to access, estimate a rough body fat percentage from just height, weight, and age.
Checking for skinny-fat
If your BMI is normal but you feel soft, look at body fat percentage and lean mass together to get a sense of whether you may be low on muscle.
Setting a more specific weight-loss goal
Target fat mass (kg) itself instead of plain body weight to build a more concrete diet plan.
Tracking workout progress
Measure periodically under the same conditions to confirm that fat is dropping and muscle is rising even when your weight stays the same.
Tips
- The trend over time matters more than any single number. Measure periodically under the same conditions and watch the direction it moves.
- Women carry more essential fat than men for menstruation, pregnancy, and hormones, so the normal body fat range itself is higher. Do not confuse the male and female standards.
- To cut body fat, the key is not only diet and cardio but also strength training to preserve lean mass (muscle).
- If you need a more accurate value, use body-composition analysis (such as an InBody scan) at a gym or clinic, or a caliper measurement. This calculator is for a quick gauge.
- The Deurenberg formula is based on BMI, so people with very high or very low muscle mass will see a larger gap from their real body fat. Bodybuilders and frail or elderly people should treat it as reference only.
- Too low a body fat percentage is not necessarily good either. Falling below essential fat (about 3–5% for men, about 10–13% for women) can cause hormonal and immune problems.
FAQ
What formula is used to calculate body fat percentage?
It uses the Deurenberg formula: body fat (%) = 1.2 × BMI + 0.23 × age − 10.8 × sex (male 1, female 0) − 5.4. BMI is calculated first from your height and weight.
Why does this calculator differ from my body-composition scan?
The Deurenberg formula is a statistical estimate based on BMI, so it can differ from your actual body composition. The gap is larger if you have a lot of muscle or very little. Measure with a body-composition analyzer for an accurate value.
Why are the normal body fat ranges different for men and women?
Women physiologically need more fat than men to maintain reproductive function and hormones. So even at the same "fitness" band, the normal range for women is set higher.
What body fat percentage is healthy?
Generally, around 14–18% for men and 21–25% for women is considered a good level. The ideal range can vary with your activity level and goals (general health versus athletic performance).
What are fat mass and lean mass?
Fat mass is the weight of fat in your body; lean mass is the weight of everything but fat — muscle, bone, water, and organs. More lean mass tends to mean a higher basal metabolic rate.
Do I have to enter my age?
Yes. The formula includes an age term, so at the same BMI, an older age yields a higher estimated body fat percentage. Enter your age in years.
Is my input saved?
No. All calculations happen in your browser, and your input is never sent to a server.