Health & Fitness

Body Fat Percentage Calculator

This calculator estimates body fat percentage with the Deurenberg equation, which combines BMI, age, and sex. It also multiplies that percentage by your weight to report an estimated fat mass in kilograms.

What this calculator does

The Body Fat Percentage Calculator estimates your result instantly from the values you enter, using standard health & fitness formulas. This calculator estimates body fat percentage with the Deurenberg equation, which combines BMI, age, and sex. It also multiplies that percentage by your weight to report an estimated fat mass in kilograms. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate rather than a certified or official figure.

Body Fat Percentage Calculator

Result

—
Body Fat %
—
Fat Mass (kg)

About Body Fat Percentage Calculator

The Body Fat Percentage Calculator computes BMI from your height and weight, then applies the Deurenberg equation: 1.20 times BMI, plus 0.23 times age, minus 10.8 for males, minus 5.4. Negative results are set to zero.

The estimated percentage is multiplied by your weight to give a fat mass in kilograms. Both figures are shown to one decimal place.

Formula & Mathematical Calculation

Body Fat % = f(Sex, Age (years), Height (cm), Weight (kg))

Calculated according to standard health formulas implemented in the calculator core.

Calculation Example

Choose Male, age 30, height 170 cm, weight 70 kg. BMI = 70 ÷ 1.7² = 24.22.

Body fat = 1.20 × 24.22 + 0.23 × 30 - 10.8 - 5.4 = 19.8 percent. Fat mass = 70 × 19.8 ÷ 100 = 13.8 kg. The boxes show 19.8 % and 13.8 kg.

Key Benefits

  • Estimates body fat percentage from height, weight, age, and sex using the Deurenberg equation.
  • Converts that percentage into an estimated fat mass in kilograms.
  • Clamps negative estimates to zero so the output stays sensible.
  • Free, browser-based, and requires no sign-up.

How to Use this Calculator

  1. Select sex and age
    Choose Male or Female and enter your age in years.
  2. Enter height and weight
    Type your height in centimeters and your weight in kilograms.
  3. Calculate
    Select Calculate to see the Body Fat % and Fat Mass (kg) estimates.

Assumptions & Limitations

What the calculation assumes

  • Every value you enter is treated as an exact, known amount.
  • Any rate or interval you enter is assumed to hold for the whole period unless the form asks for it separately.
  • Results use standard published formulas and account only for the values entered above.
  • Rounding is applied for display; the underlying calculation uses your full precision.
  • Results are returned in the same units you enter, unless the tool states the output unit.

What it does not cover

  • Body Fat Percentage Calculator produces a calculated result for reference and learning, not a certified or official measurement.
  • Real-world outcomes differ when tolerances, rounding rules or local standards apply.
  • Definitions and standards vary by region and change over time; verify the convention that applies to your case.
  • Figures are only as accurate as the inputs you supply — check them before acting on the result.
  • For work where the result carries real consequences, confirm it against an authoritative source.

Frequently Asked Questions

It uses the Deurenberg equation, which is based on BMI, age, and sex rather than skinfold or tape measurements.

For males the equation subtracts an extra 10.8, so a male and female with the same BMI and age get different estimates.

The estimated body fat percentage is multiplied by your entered weight and divided by 100.

Yes. If the equation produces a negative number, the tool sets it to zero.

Free to use, no account needed. Calculations run in your browser, so nothing you type is sent to a server. Results are estimates — how we build and check our calculators.