Quick BMI Calculator: Your Body Mass Index in Seconds
A free, accurate BMI calculator - enter your height and weight to see your body mass index, weight category and healthy weight range instantly. Nothing is stored.
BMI Calculator
Your BMI Result
Your BMI indicates that you may be overweight according to WHO guidelines. This may increase your risk of developing certain health conditions.
Accurate Calculations
Our BMI calculator uses the most up-to-date formula recommended by health professionals worldwide for precise results.
Personalized Insights
Receive tailored feedback based on your BMI results, including what they mean for your overall health and wellbeing.
Private & Secure
Your data never leaves your device. We prioritize your privacy and don't store any of your personal information.
Understanding Your BMI
Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m² where kg is a person's weight in kilograms and m² is their height in meters squared.
A high BMI can be an indicator of high body fat and can be used to screen for weight categories that may lead to health problems. However, BMI is not a diagnostic tool and should be used alongside other measurements.
| BMI Range | Weight Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Increased risk for certain health conditions |
| 18.5 - 24.9 | Normal weight | Lowest risk for health problems |
| 25.0 - 29.9 | Overweight | Increased risk for heart disease, high blood pressure, type 2 diabetes |
| 30.0 - 34.9 | Obesity (Class 1) | High risk for health problems |
| 35.0 - 39.9 | Obesity (Class 2) | Very high risk for health problems |
| 40.0 and above | Severe Obesity (Class 3) | Extremely high risk for serious health problems |
It's important to note that BMI is just one measure of health. Factors like muscle mass, bone density, ethnicity, and age can influence how accurately BMI reflects body fat levels. Always consult with a healthcare professional for a comprehensive health assessment.
How Accurate Is BMI?
BMI is the fastest health screen there is, but it is an estimate, not a measurement of body fat. The formula only knows your height and weight - it cannot tell muscle from fat, or where that fat sits. Studies comparing BMI against DEXA scans typically find it lands within about 5-10 percentage points of true body fat for the average adult, which is fine for population screening and rough enough that any single person can be misclassified.
The most accurate BMI calculator is simply one that uses the correct formula and honest height and weight - there is no "better" version of the equation. What improves accuracy is adding a second measurement:
- Muscular build? BMI will overstate your risk. Check your body fat percentage instead, and see how the body fat measurement methods compare on accuracy.
- Carrying weight around the middle? BMI misses fat distribution entirely. Your waist-to-hip ratio predicts cardiovascular risk better - we compare the two in waist-to-hip ratio vs. BMI.
- Older adult? Muscle loss means BMI can look healthy while body composition has shifted. Body composition is the more useful lens.
Used the way it was designed - as a first-pass screen that flags who should look closer - BMI is accurate enough. Used as a verdict on one person's health, it is not. Run the quick BMI calculation above, then use one of the follow-up measures to check whether the number is telling you the truth. For the full picture, read how accurate BMI really is.