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BMI Calculator

Calculate Body Mass Index with age & gender, view healthy weight range, BMI Prime and Ponderal Index instantly.

Gender

Male Female

Age (18–100)

yrs

Height

cm

Weight

kg

Calculation Result

What is BMI?

Body Mass Index (BMI) is a universal screening tool developed to estimate body fat percentage using only height and weight, endorsed by WHO and CDC. This calculator collects your gender and age for reference; BMI baseline classification is consistent for all adults aged 18–100 regardless of gender. It supports both Metric and US customary units, and computes three supplementary metrics: healthy weight range, BMI Prime, and Ponderal Index.

Metric BMI Formula: BMI = weight (kg) / height(m)²
US Unit BMI Formula: BMI = (weight(lbs) × 703) / height(in)²

Supplementary Metric Formulas

Healthy Weight Range

Calculates min/max weight for BMI 18.5 ~ 25 at your height, converted to your selected unit (kg / lbs).

BMI Prime

Formula: BMI ÷ 25. Value <1 = Normal/Underweight; >1 = Overweight/Obese.

Ponderal Index

Formula: weight(kg) / height(m)³. More accurate for extremely tall/short people than BMI.

Official BMI Classification Standards

Underweight

BMI < 18.5

Normal

18.5 – 24.9

Overweight

25.0 – 29.9

Obese

≥ 30.0

Step-by-Step Usage Guide

1 Select unit system via top tabs: US Units (feet/in + lbs) or Metric Units (cm + kg).
2 Choose your gender (Male / Female) and input valid age between 18–100.
3 Input your exact height and weight; decimal values are supported for precise calculation.
4 Click green Calculate BMI button to generate full results instantly.
5 View gender/age info, large BMI number, linear color slider, healthy weight range, BMI Prime and Ponderal Index.
6 Click Clear button to reset all input values and slider position for new calculation.

BMI Limitations & Notes

BMI cannot distinguish muscle mass, visceral fat and subcutaneous fat; athletes with high muscle often show overweight results.
Standard BMI ranges apply to adults 18–100; not applicable for children, adolescents under 18, pregnant women or people with physical disabilities.
Gender is only recorded as reference data; WHO adult BMI classification standards do not differ between men and women.
BMI only acts as preliminary screening; combine waist circumference, blood test results for full health assessment.
BMI Prime and Ponderal Index provide supplementary reference data but cannot replace professional medical diagnosis.