BMI Calculator
Calculate your Body Mass Index (BMI) and find your healthy weight range. Free BMI calculator with weight category and health tips.
BMI and adult interpretation
NHS: adult BMI is unsuitable during pregnancy, with eating disorders or conditions affecting height. It cannot distinguish muscle from fat; ethnicity can affect risk interpretation. These generic categories and the body-fat approximation are not individualized advice.
Metric and imperial measurements have separate drafts. Switching units clears results; enter measurements in the selected units.
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Method and limits
BMI = kg ÷ height in metres squared. Adult categories use the unrounded BMI; the reference interval is 18.5 ≤ BMI < 25.
Adult interpretation starts at 18. The body-fat approximation starts at 20: 1.2 × BMI + 0.23 × age − 10.8 × sex − 5.4, with sex = 1 for male and 0 for female. It does not measure fat.
Full numerical precision is retained until display. Unit conversions use 1 in = 2.54 cm and 1 lb = 0.45359237 kg.
This calculator does not save the measurements you enter. Other page and site services have their own data handling.
About BMI Calculator
Calculate your Body Mass Index (BMI) to assess if you're at a healthy weight. Supports both metric (kg/cm) and imperial (lbs/ft) measurements. Includes BMI categories and health recommendations.
BMI and adult interpretation NHS: adult BMI is unsuitable during pregnancy, with eating disorders or conditions affecting height. It cannot distinguish muscle from fat; ethnicity can affect risk interpretation. These generic categories and the body-fat approximation are not individualized advice. This calculator does not save the measurements you enter. Other page and site services have their own data handling.
80 kg and 200 cm give BMI 20.0.
NHS: adult BMI is unsuitable during pregnancy, with eating disorders or conditions affecting height. It cannot distinguish muscle from fat; ethnicity can affect risk interpretation. These generic categories and the body-fat approximation are not individualized advice.
Use Cases
How to use
Select your preferred unit system (metric or imperial)
Enter your height
Enter your weight
View your BMI and weight category instantly
Choose units, enter measurements and review the method and limits with the result.
Pro Tips
- BMI is a general indicator - athletes may have higher BMI due to muscle mass
- Check your BMI periodically to track health progress
- Consult a healthcare provider for personalized health advice
- Metric and imperial measurements have separate drafts. Switching units clears results; enter measurements in the selected units.
Troubleshooting
BMI seems too high
If you exercise regularly and have significant muscle mass, BMI may overestimate body fat.
Getting different results elsewhere
Ensure you're using the same units (metric vs imperial) and accurate measurements.
Frequently Asked Questions
A healthy BMI is typically between 18.5 and 24.9. Below 18.5 is underweight, 25-29.9 is overweight, and 30+ is obese. BMI = kg ÷ height in metres squared. Adult categories use the unrounded BMI; the reference interval is 18.5 ≤ BMI < 25. NHS: adult BMI is unsuitable during pregnancy, with eating disorders or conditions affecting height. It cannot distinguish muscle from fat; ethnicity can affect risk interpretation. These generic categories and the body-fat approximation are not individualized advice.
BMI doesn't account for muscle mass, age, or body composition. Athletes and elderly may have different healthy ranges. BMI = kg ÷ height in metres squared. Adult categories use the unrounded BMI; the reference interval is 18.5 ≤ BMI < 25. NHS: adult BMI is unsuitable during pregnancy, with eating disorders or conditions affecting height. It cannot distinguish muscle from fat; ethnicity can affect risk interpretation. These generic categories and the body-fat approximation are not individualized advice.
Checking monthly is sufficient for tracking progress. Daily weight fluctuations are normal. BMI = kg ÷ height in metres squared. Adult categories use the unrounded BMI; the reference interval is 18.5 ≤ BMI < 25. NHS: adult BMI is unsuitable during pregnancy, with eating disorders or conditions affecting height. It cannot distinguish muscle from fat; ethnicity can affect risk interpretation. These generic categories and the body-fat approximation are not individualized advice.
Consult a healthcare provider for personalized advice on diet, exercise, and health goals. BMI = kg ÷ height in metres squared. Adult categories use the unrounded BMI; the reference interval is 18.5 ≤ BMI < 25. NHS: adult BMI is unsuitable during pregnancy, with eating disorders or conditions affecting height. It cannot distinguish muscle from fat; ethnicity can affect risk interpretation. These generic categories and the body-fat approximation are not individualized advice.
They show the stated arithmetic assumptions, not an individual diagnosis or a measured energy requirement.
The adult category uses the unrounded BMI. The number shown is rounded to one decimal, so read it together with the category and method.