BMI Calculator

Calculate body mass index, healthy weight range, BMR, daily calories, and estimated body fat.

Body mass index inputs

Enter height and weight, then choose a reference range for the BMI category.

BMI result

24.2

Healthy range

BMI is within the reference healthy range.

Reference range: 18.5 to 24.9

Healthy weight range

53.5-72.2 kg

Based on the selected BMI reference range.

Height

170 cm

Weight

70 kg

Estimated body fat

19.8%

Deurenberg formula estimate.

BMR

1,618 kcal/day

Mifflin-St Jeor estimate.

Daily calories

2,507 kcal/day

Moderate activity

What is the BMI calculator?

This calculator estimates Body Mass Index from height and weight, then helps interpret the result with WHO, Asian, and Korean adult reference ranges. The existing Korean utility page also connects BMI with BMR, daily calorie need, estimated body-fat percentage, target weight, and saved measurement history.

BMI formula

BMI = weight in kg / height in m squared. A person who is 170 cm and 70 kg has BMI = 70 / (1.7 x 1.7) = 24.2.

BMI reference ranges

WHO, Asian, and Korean cutoffs

  • WHO: underweight below 18.5, normal 18.5 to 25, overweight 25 to 30, obese 30 or higher.
  • Asian reference: underweight below 18.5, normal 18.5 to 23, overweight 23 to 27.5, obese 27.5 or higher.
  • Korean reference: underweight below 18.5, normal 18.5 to 23, overweight 23 to 25, obese 25 or higher.
  • Because Koreans and other Asian populations can have higher metabolic risk at lower BMI than Western populations, the Asian or Korean cutoffs are often more conservative than WHO cutoffs.
  • The 170 cm and 70 kg example, BMI 24.2, is normal by WHO but above the Korean normal cutoff, so users should read the result against the selected standard.

Additional health metrics

  • BMR uses the Mifflin-St Jeor equation: men = 10 x kg + 6.25 x cm - 5 x age + 5; women = 10 x kg + 6.25 x cm - 5 x age - 161.
  • Daily calorie need multiplies BMR by activity factors: sedentary 1.2, light 1.375, moderate 1.55, active 1.725, and very active 1.9.
  • Body-fat estimate uses the Deurenberg equation: 1.2 x BMI + 0.23 x age - 10.8 x gender factor - 5.4.
  • For target-weight analysis, the source logic treats safe weekly loss as 0.5 to 1.0 kg and safe weekly gain as 0.25 to 0.5 kg.

How to use BMI responsibly

Measurement and interpretation

  • Measure height accurately without shoes and weigh under consistent conditions, ideally in the morning after restroom use.
  • BMI is a screening metric, not a diagnosis. It does not account for muscle mass, bone density, pregnancy, edema, or fat distribution.
  • Athletes can have high BMI with low body fat, and people with low muscle mass can have normal BMI with higher health risk.
  • For pregnancy, pediatric growth, chronic disease, or major body-composition concerns, follow clinician guidance instead of relying on adult BMI cutoffs alone.