Evidence-informed tracking

Body fat calculator

Fat-Calculator.com is a simple and intuitive tool designed to help you assess your body composition and overall health. It provides key metrics to support your fitness journey—whether you are aiming to lose weight, build muscle, or maintain a healthy lifestyle.

  • Instant BMI, body fat %, fat mass, and lean mass updates.
  • Metric & imperial toggles with both sliders and manual inputs.
  • Guideline tables inspired by WHO, ACE, and ACSM references.
Start calculating View references
Live BMI 24.2

Status: normal

Body fat % 18.6%

Fat mass 13.0 kg

Lean mass 57.0 kg

Healthy habits start with awareness.

Interactive inputs

Enter your details

Adjust sliders or type in exact values. Every edit updates BMI and Deurenberg body fat estimates.

Years
Gender
Units:
Metric (cm, kg)
Height
cm
Weight
kg

Results

BMI 24.2
Body fat 18.6%
Fat mass 13.0 kg
Lean mass 57.0 kg
Jump to detailed breakdown

*For a more accurate body fat percentage
use the U.S. Navy calculator on

this page

Instant feedback

Live BMI gauge

Track how tweaks to your entries shift the gauge and the BMI category beneath it.

24.2
BMI

  • Very Severely Underweight

    < 16.0

  • Severely Underweight

    16.0 - 16.9

  • Underweight

    17.0 - 18.4

  • Normal

    18.5 - 24.9

  • Overweight

    25.0 - 29.9

  • Obese Class I

    30.0 - 34.9

  • Obese Class II

    35.0 - 39.9

  • Obese Class III

    >= 40.0

Quick context

  • The WHO normal range is 18.5 - 24.9 BMI. You are currently normal.
  • Body fat estimates rely on the Deurenberg equation and work best for adults between 18 and 65.
  • Lean mass is 57.0 kg; compare it to strength or muscle-building goals.

Use these numbers as a starting point when talking with a coach or clinician.

Body Fat Percentage Estimate
Your Body Parameters
Sex: male Age: 25 yrs
Height: 170 cm Weight: 70.0 kg
Fat Mass: 13.0 kg Lean Mass: 57.0 kg
Body Fat: 18.6 % BMI: 24.2
WHO / NIH Guidelines, Gallagher et al.
Category Body Fat Current weight
Underfat under 8 % Under 61.9 kg
Healthy 8 to 19.9 % 61.9 - 71.2 kg Current: 70.0 kg
Overfat 20 to 24.9 % 71.2 - 76.0 kg
Obese 25 % and over Over 76.0 kg
1) American Council on Exercise male, Body Fat 18.6 %
Category Body Fat Current weight
Essential 2 to 5.9 % Under 60.6 kg
Athletes 6 to 13.9 % 60.6 - 66.2 kg
Fitness 14 to 17.9 % 66.2 - 69.5 kg
Acceptable 18 to 24.9 % 69.5 - 76.0 kg Current: 70.0 kg
Obese 25 % and over Over 76.0 kg
2) WHO / NIH Guidelines, Gallagher et al. male, 25 yrs, Body Fat 18.6 %
Category Body Fat Current weight
Underfat under 8 % Under 61.9 kg
Healthy 8 to 19.9 % 61.9 - 71.2 kg Current: 70.0 kg
Overfat 20 to 24.9 % 71.2 - 76.0 kg
Obese 25 % and over Over 76.0 kg
3) American College of Sports Medicine* male, 25 yrs, Body Fat 18.6 %
Category Body Fat Current weight
Very Lean 4 to 7.9 % Under 61.9 kg
Excellent 8 to 11.4 % 61.9 - 64.4 kg
Good 11.5 to 15.7 % 64.4 - 67.7 kg
Fair 15.8 to 19.6 % 67.7 - 70.9 kg Current: 70.0 kg
Poor 19.7 to 24.9 % 70.9 - 76.0 kg
Very Poor 25 % and over Over 76.0 kg
* This table was adapted from tables 4.2 and 4.3 on pages 72 and 73 respectively, of ACSM's Health-Related Physical Fitness Assessment manual, 5th Edition.

Body fat calculator

Fat-Calculator.com is a simple tool for estimating body-composition metrics from a few basic inputs. It is intended for general informational and educational use—for example, to get a rough snapshot of body composition alongside other measurements.

What it does

The Body Fat Calculator estimates the following from your inputs:

  • BMI (Body Mass Index) — weight relative to height.
  • Body fat percentage — an estimate of the proportion of body weight that is fat, based on the Deurenberg BMI-based formula.
  • Fat mass — estimated total weight of body fat.
  • Lean mass — estimated weight of non-fat tissue.

For example, with age 25, male, height 170 cm, and weight 70 kg, the calculator returns a BMI of about 24.2, a body fat estimate of about 18.6%, fat mass of about 13.0 kg, and lean mass of about 57.0 kg.

How to use it

  • Enter your age, sex, and units (metric or imperial).
  • Set your height and weight using the sliders or manual entry.
  • The calculator displays BMI, body fat percentage, fat mass, and lean mass instantly.

Why use it

The tool gives a quick estimate of body composition from height, weight, age, and sex. Because it is based on a BMI-derived formula, it does not account for factors such as high muscle mass in athletes, and it is not a body-composition measurement. Methods such as DEXA provide direct measurement.

Sources & further reading

  • Deurenberg P, Weststrate JA, Seidell JC. Body mass index as a measure of body fatness: age- and sex-specific prediction formulas. Br J Nutr. 1991;65(2):105–114. PMID 1859365 — body-fat estimation formula.
  • World Health Organization. Body mass index (BMI) classification. who.int — BMI categories.
  • American Council on Exercise (ACE). Percent body fat norms. acefitness.org — body-fat reference ranges.