Free tool
BMI calculator
Body mass index from your height and weight, with the healthy range for someone your height.
— BMI
Fill in the fields to see your result.
- Healthy weight for your height
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- Your height
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- Formula
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BMI is a rough screen, not a diagnosis. It does not tell muscle from fat, so a lifter and a sedentary person can share a number and not a risk.
FAQ
Common questions
How is BMI calculated?
BMI is your weight divided by your height squared. In pounds and inches, the formula is: weight (lbs) / height (inches) squared x 703. In metric, it is weight (kg) / height (m) squared. A BMI between 18.5 and 24.9 is considered normal weight, 25 to 29.9 is overweight, and 30 or above is obese.
What is a healthy BMI?
A BMI between 18.5 and 24.9 is generally considered normal weight. But BMI is a screening tool, not a diagnostic one. It does not account for muscle mass, bone density, age, sex, or body fat distribution. Two people with the same BMI can have very different health profiles.
Is BMI accurate for everyone?
No. BMI has known limitations. It can overestimate body fat in athletes and people with high muscle mass, and underestimate it in older adults who have lost muscle. It also does not reflect where your body stores fat, which matters a lot for health risk. It is a useful starting point, not the final word.
What are the BMI categories?
The standard BMI categories are: Underweight (below 18.5), Normal weight (18.5 to 24.9), Overweight (25.0 to 29.9), Obese Class I (30.0 to 34.9), Obese Class II (35.0 to 39.9), and Obese Class III (40.0 and above).
Should I make health decisions based on BMI alone?
No. BMI is one piece of a much larger puzzle. Your doctor will also consider your waist circumference, body composition, blood work, family history, lifestyle, and overall health before making any recommendations. BMI is a conversation starter, not a diagnosis.
What is the difference between BMI and body fat percentage?
BMI is a ratio of your weight to your height. Body fat percentage tells you what portion of your total weight is actually fat tissue. BMI is easier to calculate but less precise. Body fat percentage requires specialized tools like DEXA scans, calipers, or bioelectrical impedance scales, but gives a more accurate picture of your body composition.