BMI Calculator
Find your Body Mass Index and healthy weight range. Switch between imperial and metric in one click. No signup, no ads.
Your measurements
Enter your weight and height to see your BMI.
How is BMI calculated?
Body Mass Index
Variables
Body Mass Index-The calculated result, in kg/m^2
Weight-Your body weight in kilograms
Height-Your body height in meters
BMI Categories (WHO Classification)
| Category | BMI Range | Health Risk |
|---|---|---|
| Severe underweight | < 16.0 | High |
| Moderate underweight | 16.0 - 16.9 | Moderate |
| Mild underweight | 17.0 - 18.4 | Slightly increased |
| Normal weight | 18.5 - 24.9 | Low |
| Overweight | 25.0 - 29.9 | Slightly increased |
| Obesity Class I | 30.0 - 34.9 | Increased |
| Obesity Class II | 35.0 - 39.9 | High |
| Obesity Class III | >= 40.0 | Very high |
Frequently Asked Questions about the BMI Calculator
What is a healthy BMI for adults?
The World Health Organization defines a healthy BMI as 18.5 to 24.9 for adults. BMI alone does not account for muscle mass, bone density, or body fat distribution, so it is a screening tool, not a diagnosis.
How is BMI calculated?
BMI is your weight in kilograms divided by your height in meters squared. In imperial units, multiply weight in pounds by 703, then divide by height in inches squared. This calculator handles both automatically.
Does BMI work the same for everyone?
No. BMI does not distinguish between muscle and fat, and it can overestimate body fat in athletes or underestimate it in older adults who have lost muscle. Children, pregnant people, and very tall or very short adults need different references.
What should I do if my BMI is outside the healthy range?
Use BMI as one signal among many. Talk to a doctor or a registered dietitian who can look at body composition, lifestyle, family history, and lab results before suggesting changes.
Is BMI valid for athletes?
Often not. Muscle is denser than fat, so a muscular person can land in the overweight range without excess body fat. For athletes, body fat percentage and waist-to-hip ratio are better indicators.
What BMI is considered obese?
The WHO classifies a BMI of 30 or above as obesity. Class I covers 30 to 34.9, Class II covers 35 to 39.9, and Class III covers 40 and above.
Does this calculator save my data?
Your inputs stay in your browser. Nothing is sent to a server or shared. Your last values are remembered locally so the form is filled in next time you visit.
How accurate is this BMI calculator?
It uses the standard WHO formula. Accuracy depends on the precision of your weight and height measurements. Round numbers like 70 kg and 175 cm work fine for most uses.
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