Free BMI Calculator
Calculate your Body Mass Index instantly using height and weight. See your BMI category, healthy weight range, and what your result means — free, no account needed.
| Category | BMI range | Status |
|---|---|---|
| Underweight | < 18.5 | |
| Normal weight | 18.5–25 | You are here |
| Overweight | 25–30 | |
| Obese (Class I) | 30–35 | |
| Obese (Class II) | 35–40 | |
| Obese (Class III) | ≥ 40 |
BMI is a screening tool, not a medical diagnosis. Consult a healthcare provider for personalized health advice.
BMI doesn't account for muscle mass, bone density, age, or fat distribution. Athletes often have a "high" BMI despite being very healthy. Always discuss results with your doctor.
How it works
How to calculate your BMI
Choose your units
Select imperial (feet & pounds) or metric (cm & kg) — whichever you prefer.
Enter your height
Type in your height accurately. Even a small difference affects your BMI result.
Enter your weight
Use your current weight. For accuracy, weigh yourself in the morning before eating.
Read your result
See your BMI, category, healthy weight range, and how much to gain or lose if needed.
FAQ
BMI calculator questions
Common questions about BMI and what your number means.
What is BMI?+
BMI (Body Mass Index) is a number calculated from your height and weight. It's a widely used screening tool to categorize weight status — underweight, normal, overweight, or obese. It does not directly measure body fat, but correlates with more direct measures of body fat for most people.
What is a healthy BMI range?+
For most adults, a BMI between 18.5 and 24.9 is considered healthy. A BMI under 18.5 is classified as underweight, 25–29.9 as overweight, and 30 or above as obese. These thresholds are the same for men and women, though different ranges apply for children.
Is BMI accurate for everyone?+
BMI has known limitations. It can overestimate body fat in athletes and muscular individuals, and underestimate it in older adults who have lost muscle mass. It also doesn't account for how fat is distributed — belly fat carries more health risk than fat elsewhere. Use it as a starting point, not a complete health assessment.
What's the difference between BMI and body fat percentage?+
BMI is calculated purely from height and weight — it's quick and requires no special equipment. Body fat percentage directly measures what proportion of your body is fat vs. lean mass. For a fuller picture of health, body fat percentage (measured by DEXA, hydrostatic weighing, or calipers) is more informative.
Does BMI apply to children?+
For children and teens (ages 2–19), BMI is calculated the same way but interpreted differently using age- and sex-specific percentiles, not the fixed adult ranges. A BMI in the 85th–94th percentile is considered overweight for children; 95th percentile or above is obese.
What should I do if my BMI is outside the healthy range?+
A BMI outside the healthy range is a signal to speak with a healthcare provider — not a diagnosis. Many factors affect health beyond BMI, including fitness level, diet, sleep, and genetics. Your doctor can recommend personalized next steps based on your full health picture.
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