Free Online BMI Calculator
Calculate your BMI and get guidance based on US adult standards (CDC/WHO)
US Adult Standard (CDC)
Units
lb
Options
Enter a height between 80 and 250 cm
Enter a weight between 20 and 300 kg
BMI Categories (Adults, CDC/WHO)
BMI Category Risk
< 18.5 Underweight Higher risk of nutritional deficiency
18.5 – 24.9 Healthy weight Lower risk
25.0 – 29.9 Overweight Moderate risk
≥ 30.0 Obesity Higher risk
My BMI History
All calculations run locally in your browser. No personal health data is collected or uploaded.
# Date Units Height Weight BMI Category Action
No saved BMI records yet.
Formula
BMI = weight(kg) ÷ height²(m). Example: 65 kg at 170 cm → BMI = 65 ÷ (1.7 × 1.7) = 22.5.
Important Notes
BMI does not distinguish fat from muscle (athletes can be classified as overweight). Standards differ for pregnancy, older adults, and children/teens (age- and sex-specific growth charts are used).
Health Guidance (Diet & Activity)
General guidance for adults. If you have medical conditions, consult a clinician.
Category Diet Activity
Underweight Increase nutrient-dense foods and protein Strength training to build lean mass
Healthy weight Balanced diet; keep added sugar/salt moderate Mix cardio and strength
Overweight Reduce total calories; limit refined carbs Prioritize regular aerobic activity
Obesity Create a sustainable calorie deficit; avoid sugary drinks Start with low-impact, progress gradually
Data Sources & Validation
This tool uses the standard BMI formula and references the following sources:
References
  1. CDC. Adult BMI Categories
  2. MedlinePlus (NIH). Body mass index
  3. World Health Organization (WHO). Obesity and overweight (Fact sheet)