BMI Calculator
Calculate your Body Mass Index (BMI) to check if you are at a healthy weight
How to Use This BMI Calculator
- Enter your age (BMI interpretation can vary by age group)
- Select your gender
- Enter your height using your preferred unit (cm, inches, or feet/inches)
- Enter your weight in kg or pounds
- Click 'Calculate BMI' to see your result, category, and healthy weight range
Example: A 35-year-old male who is 5'10" (178 cm) and weighs 180 lbs (82 kg) has a BMI of 25.8, placing him in the 'Overweight' category. His healthy weight range would be 129-174 lbs for a BMI between 18.5-25.
Tip: BMI is a screening tool, not a diagnostic one. Athletes with high muscle mass may have elevated BMI while being very healthy.
Why Use a BMI Calculator?
BMI provides a quick, standardized way to screen for weight categories that may indicate health risks. It's the first step in assessing weight-related health.
- General health screening during routine checkups
- Understanding if your weight falls within healthy ranges
- Tracking weight changes over time with a standardized measure
- Setting realistic weight goals based on height
- Insurance or medical evaluations requiring BMI documentation
- Starting point for deeper body composition discussions with your doctor
Understanding Your Results
BMI categories are set by the World Health Organization and are associated with statistical health risk levels.
| Result | Meaning | Action |
|---|---|---|
| BMI < 18.5 | Underweight | Consult a doctor. May indicate malnutrition, eating disorders, or other health issues. |
| BMI 18.5-24.9 | Normal Weight | Healthy range. Focus on maintaining through balanced diet and regular activity. |
| BMI 25-29.9 | Overweight | Increased health risks. Consider lifestyle changes - diet improvements and increased exercise. |
| BMI 30-34.9 | Obese Class I | High health risk. Consult healthcare provider about weight management strategies. |
| BMI 35+ | Obese Class II/III | Very high health risk. Medical intervention may be recommended. Seek professional guidance. |
Meaning: Underweight
Action: Consult a doctor. May indicate malnutrition, eating disorders, or other health issues.
Meaning: Normal Weight
Action: Healthy range. Focus on maintaining through balanced diet and regular activity.
Meaning: Overweight
Action: Increased health risks. Consider lifestyle changes - diet improvements and increased exercise.
Meaning: Obese Class I
Action: High health risk. Consult healthcare provider about weight management strategies.
Meaning: Obese Class II/III
Action: Very high health risk. Medical intervention may be recommended. Seek professional guidance.
Note: BMI doesn't distinguish between muscle and fat mass. A muscular athlete and someone with excess body fat could have the same BMI.
About BMI Calculator
Formula
BMI = weight (kg) / height (m)^2 To calculate manually: divide your weight in kilograms by your height in meters squared. For pounds and inches: (weight in lbs x 703) / (height in inches)^2.
Current Standards: WHO classifications: Underweight (<18.5), Normal (18.5-24.9), Overweight (25-29.9), Obese Class I (30-34.9), Obese Class II (35-39.9), Obese Class III (40+). Some Asian countries use lower thresholds due to different body compositions.
Frequently Asked Questions
Is BMI accurate for everyone?
BMI has limitations for certain groups. It overestimates body fat in muscular athletes and underestimates it in elderly people who have lost muscle mass. It also doesn't account for ethnic differences in body composition - people of Asian descent may have higher health risks at lower BMI levels, while some Pacific Islander populations may be healthy at higher BMIs. Use BMI as a starting point, not the final word.
I'm muscular and my BMI says I'm overweight. Should I worry?
If you're athletic with significant muscle mass, BMI may misclassify you. Muscle weighs more than fat by volume. Better assessments for you would include body fat percentage (Navy tape test, DEXA scan), waist-to-hip ratio, or waist circumference. If your waist is under 40 inches (men) or 35 inches (women) and your blood pressure and blood sugar are normal, a 'high' BMI may not indicate excess fat.
What health risks are associated with high BMI?
Statistically, BMI above 25 correlates with increased risk of: type 2 diabetes, cardiovascular disease, high blood pressure, certain cancers (breast, colon), sleep apnea, osteoarthritis, fatty liver disease, and gallbladder disease. These risks increase progressively with higher BMI categories. However, physically active overweight individuals often have better health markers than sedentary normal-weight people.
How much weight do I need to lose to change my BMI category?
For most adults, losing about 5-7 pounds changes BMI by approximately 1 point. Someone with a BMI of 27 who is 5'8" would need to lose roughly 15-20 pounds to reach the normal weight category. Even modest weight loss of 5-10% of body weight significantly improves health markers like blood pressure and blood sugar, even if you remain in the overweight category.
Should I use BMI to set my goal weight?
BMI provides a reasonable range to aim for, but your ideal weight depends on individual factors. A BMI of 22-23 is often cited as optimal for longevity, but any weight within the 18.5-24.9 range is considered healthy. Focus on how you feel, your energy levels, and health markers rather than hitting an exact number. Sustainable habits matter more than rapid weight loss to hit a BMI target.