Use this BMI Calculator to calculate your Body Mass Index based on height and weight. BMI is commonly used to assess whether a person falls within an underweight, healthy weight, overweight, or obesity range.
BMI (Body Mass Index) is calculated as weight divided by height squared. For US units: BMI = (weight in lbs × 703) ÷ (height in inches)². It's a screening tool used by the CDC to assess weight categories.
Disclaimer: This BMI calculator provides estimates for informational purposes only. Consult a healthcare professional for medical advice.
A complete guide for healthy weight assessment
You step on the scale and see a number. But what does that number really mean about your health? Your weight alone doesn't tell the whole story. Body Mass Index (BMI) provides a more complete picture by considering your height along with your weight.
BMI is a screening tool used to identify possible weight problems in adults. It's a simple calculation based on height and weight that categorizes individuals as underweight, normal weight, overweight, or obese. While not perfect, BMI is widely used by healthcare professionals.
But BMI has limitations. It doesn't distinguish between muscle and fat, and it may not be accurate for athletes, elderly individuals, or pregnant women. Understanding these limitations is important for interpreting your BMI correctly.
Use the BMI calculator above to calculate your Body Mass Index, understand what your number means, and learn how to achieve and maintain a healthy weight.
BMI is calculated by dividing your weight in kilograms by your height in meters squared. For imperial units, the formula includes a conversion factor. The result is a number that places you in a weight category.
Metric Formula:
BMI = Weight (kg) / [Height (m)]²
Imperial Formula:
BMI = [Weight (lbs) / (Height (in))²] × 703
Here's a concrete example:
BMI is divided into categories that indicate whether a person is at a healthy weight. These categories are standardized by the World Health Organization and used globally for screening purposes.
| Health Risks | Malnutrition, osteoporosis, weakened immune system |
| Recommendation | Consult healthcare provider, increase caloric intake |
Being underweight can be as unhealthy as being overweight. It may indicate malnutrition, eating disorders, or underlying health conditions. Medical evaluation is recommended.
| Health Risks | Minimal for most people |
| Recommendation | Maintain current weight with balanced diet and exercise |
This is the ideal BMI range for most adults. People in this range generally have the lowest risk of weight-related health problems. Maintain healthy habits to stay in this range.
| Health Risks | Increased risk of heart disease, diabetes, high blood pressure |
| Recommendation | Adopt healthier diet, increase physical activity |
Being overweight increases the risk of several chronic diseases. Lifestyle changes can often help reduce BMI to the normal range. Even modest weight loss provides health benefits.
| Health Risks | High risk of diabetes, heart disease, certain cancers |
| Recommendation | Medical consultation, structured weight loss program |
Obesity significantly increases health risks. Medical supervision is recommended for weight loss. A combination of diet, exercise, and sometimes medication is often needed.
| Health Risks | Very high risk of serious health complications |
| Recommendation | Comprehensive medical weight management |
Severe obesity requires comprehensive medical management. The risks of serious health complications are very high. Bariatric surgery may be considered in some cases.
| Health Risks | Extreme risk of life-threatening conditions |
| Recommendation | Intensive medical intervention, possible surgery |
This is also called morbid obesity. The health risks are extreme and life-threatening. Intensive medical intervention, including bariatric surgery, is often necessary.
BMI is a useful screening tool, but it has important limitations. Understanding these limitations helps you interpret your BMI correctly and avoid misinterpreting your health status.
Muscle vs. fat
BMI doesn't distinguish between muscle and fat. Athletes and bodybuilders may have high BMI due to muscle mass, not excess fat. For these individuals, BMI may overestimate body fat.
Age considerations
BMI may not be accurate for elderly individuals who have lost muscle mass. Older adults may have normal BMI but still have excess body fat. Other measures may be more appropriate.
Ethnicity differences
BMI cutoffs may not apply equally to all ethnic groups. Some populations have higher health risks at lower BMI levels. Ethnicity-specific adjustments may be needed.
Pregnancy
BMI is not appropriate for pregnant women. Weight gain during pregnancy is normal and necessary. Postpartum BMI should be assessed after recovery.
Children and teens
BMI is interpreted differently for children and teens. Age and gender-specific percentiles are used instead of adult categories. Pediatric BMI charts are used.
Fat distribution
BMI doesn't account for where fat is stored. Abdominal fat (visceral fat) is more harmful than fat stored elsewhere. Waist circumference provides additional information.
Because BMI has limitations, healthcare providers often use additional measures to assess body composition and health risks. These measures provide a more complete picture.
| Measure | What It Measures | Advantages |
|---|---|---|
| Waist Circumference | Abdominal fat | Assesses visceral fat risk |
| Waist-to-Hip Ratio | Fat distribution | Indicates health risk pattern |
| Body Fat Percentage | Actual fat mass | Distinguishes fat from muscle |
| Skinfold Measurements | Subcutaneous fat | Estimates body composition |
| Bioelectrical Impedance | Body composition | Quick and non-invasive |
| DEXA Scan | Bone and body composition | Most accurate measure |
BMI is calculated by dividing weight in kilograms by height in meters squared. For imperial units, multiply the result by 703. The calculator above performs this calculation automatically.
A healthy BMI is between 18.5 and 24.9 for most adults. This range is associated with normal weight and the lowest risk of weight-related health problems.
No. BMI doesn't distinguish between muscle and fat, so it may not be accurate for athletes, bodybuilders, elderly individuals, or pregnant women. Other measures may be needed for these groups.
BMI is simple, inexpensive, and non-invasive. It's a good screening tool for large populations. For individuals, it's a starting point that may be followed by more detailed assessments.
Check your BMI periodically, especially if you're actively trying to change your weight. Monthly checks can help track progress. Annual checks are sufficient for weight maintenance.
Yes. Normal BMI doesn't guarantee good health. You can have normal weight but poor diet, lack of exercise, or other risk factors. BMI is just one measure of health.
Consult your healthcare provider for personalized advice. Generally, increasing physical activity, improving diet, and making lifestyle changes can help reduce BMI. Medical supervision is recommended for significant weight loss.
The BMI calculation is the same for men and women, but health risks may differ at the same BMI. Women naturally have higher body fat percentages than men, which may affect health risk assessment.
BMI is a useful screening tool for assessing weight status, but it's not a perfect measure of health. Use it as a starting point, not the final word on your health.
If your BMI is outside the normal range, consult your healthcare provider for personalized advice. They can help you understand your specific situation and develop a plan to achieve a healthy weight.
Remember that health is about more than just a number. Focus on developing healthy habits that you can maintain long-term, rather than obsessing over a specific BMI target.