Obesity and BMI Calculator

Calculate BMI, obesity category, target weight range, and basic health-risk signals from height and weight.

BMI

26.8

Overweight

Target range

56.7-76.3 kg

BMI 18.5 to 24.9

Weight gap

5.7 kg

Above top of target range

Waist signal

Watch waist trend

92 cm

Body size inputs

Estimate BMI, weight category, target range, and waist signal.

What is the obesity calculator?

This calculator combines BMI, body-fat percentage, basal metabolic rate, total daily energy expenditure, and target calories. It keeps the Korean and Asian BMI categories from the source page and adds body-fat estimation with the US Navy Method.

Core formulas

BMI = weight kg / (height m x height m). BMR uses Mifflin-St Jeor: men = 10 x kg + 6.25 x cm - 5 x age + 5; women = 10 x kg + 6.25 x cm - 5 x age - 161.

BMI, body fat, and calorie classification

Korean and Asian BMI categories

  • Underweight: below 18.5.
  • Normal: 18.5 to 22.9.
  • Overweight: 23.0 to 24.9.
  • Obesity stage 1: 25.0 to 29.9.
  • Obesity stage 2: 30.0 to 34.9.
  • Obesity stage 3: 35.0 or higher.

Body-fat ranges and activity factors

  • Men: essential 2% to 5%, athletes 6% to 13%, healthy 14% to 17%, average 18% to 24%, obese 25% or higher.
  • Women: essential 10% to 13%, athletes 14% to 20%, healthy 21% to 24%, average 25% to 31%, obese 32% or higher.
  • TDEE activity factors are 1.2 for little exercise, 1.375 for light exercise 2 to 3 times per week, 1.55 for moderate exercise 4 to 5 times per week, 1.725 for active 6 to 7 times per week, and 1.9 for very active two-a-day training.
  • Healthy weight change is usually 0.5 to 1 kg per week, so aggressive deficits are not recommended.

Source examples

Weight-loss example

A 35-year-old man, 175 cm, 85 kg, neck 40 cm, waist 95 cm, light activity, and target 75 kg gives BMI 27.8, obesity stage 1, body fat about 28%, BMR about 1,850 kcal, TDEE about 2,544 kcal, recommended loss calories about 2,044 kcal per day, and an expected 14 weeks or 3.5 months at a 500 kcal daily deficit.

Normal and gain examples

  • A 28-year-old woman, 162 cm and 55 kg with moderate activity gives BMI 21, body fat about 23%, BMR about 1,320 kcal, and TDEE about 2,046 kcal.
  • A 42-year-old woman, 158 cm and 45 kg, target 50 kg, light activity gives BMI 18.0, underweight, body fat about 20%, BMR about 1,180 kcal, TDEE about 1,623 kcal, recommended gain calories 1,873 kcal per day, and expected 10 weeks or 2.5 months.