Body Mass Index (BMI) Calculator
Use this quick tool to estimate your body mass index from height and weight.
What does “calculate body mass” usually mean?
In most health contexts, people use “calculate body mass” to mean calculating Body Mass Index (BMI). BMI is a simple screening number based on your weight and height. It does not directly measure body fat, but it gives a quick estimate to help identify whether someone may be underweight, at a healthy weight, overweight, or in the obesity range.
How BMI is calculated
Metric formula
BMI = weight (kg) ÷ [height (m)]²
Imperial formula
BMI = 703 × weight (lb) ÷ [height (in)]²
The calculator above handles these formulas automatically and shows your BMI category instantly. It can also estimate a healthy weight range for your height using standard BMI cutoffs.
BMI categories (adult screening ranges)
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5 to 24.9
- Overweight: BMI 25.0 to 29.9
- Obesity: BMI 30.0 and above
Important limitations to understand
BMI is useful, but it has limits. It does not distinguish between fat, muscle, bone, and water. For example, a muscular athlete can have a high BMI while still being very healthy. Older adults, pregnant individuals, and some ethnic populations may also need more personalized interpretation.
That is why BMI works best as a starting point, not a final diagnosis. For a fuller picture, combine it with waist circumference, blood pressure, lab work, activity level, sleep quality, and nutrition patterns.
How to use your result wisely
If your BMI is below healthy range
- Review calorie and protein intake.
- Consider resistance training to build lean mass.
- Talk with a clinician if unintentional weight loss occurred.
If your BMI is above healthy range
- Focus on sustainable habits rather than extreme diets.
- Increase daily movement and structured exercise.
- Prioritize sleep and stress management.
- Track trends over time instead of day-to-day fluctuations.
Practical next steps
After you calculate your body mass index, set one small action for the next 2–4 weeks: walk 20 minutes daily, reduce sugary drinks, add strength training twice per week, or improve meal consistency. Gradual improvements are more likely to stick than aggressive short-term plans.
If you have chronic health conditions such as diabetes, heart disease, thyroid disorders, or rapid weight changes, seek individualized advice from a qualified healthcare professional.