Body composition
BMI Calculator
Your Body Mass Index, against WHO classification standards.
Your Body Mass Index, against WHO classification standards.
BMI stands for Body Mass Index - a simple screening tool used worldwide to categorize body weight relative to height. It provides a quick assessment of whether you're underweight, normal weight, overweight, or obese based on standardized ranges established by the World Health Organization (WHO). While BMI doesn't directly measure body fat, it's a useful starting point for understanding your weight status and potential health risks.
The beauty of BMI is its simplicity: it requires only two measurements (height and weight) and can be calculated in seconds. However, it's important to understand that BMI is a screening tool, not a diagnostic measure. It doesn't account for muscle mass, bone density, or body composition.
That's why BMI should be used alongside other health indicators like waist circumference, body fat percentage, blood pressure, and cholesterol levels. For most people, BMI provides a reasonable estimate of health risk - studies show that higher BMI categories are associated with increased risk of cardiovascular disease, type 2 diabetes, and certain cancers.
For a more complete picture, pair BMI with a direct body fat percentage measurement and use your Total Daily Energy Expenditure (TDEE) to set calorie targets aligned with your goals.
Our calculator uses the standard BMI formula recognized by health organizations worldwide.
Body Mass Index is calculated by dividing your weight in kilograms by the square of your height in meters:
| BMI Range | Category | Health Risk |
|---|---|---|
| < 16.0 | Severely Underweight | High risk of malnutrition |
| 16.0 - 18.4 | Underweight | Moderate risk |
| 18.5 - 24.9 | Normal Weight | Low risk |
| 25.0 - 29.9 | Overweight | Moderate risk |
| 30.0 - 34.9 | Obese Class I | High risk |
| 35.0 - 39.9 | Obese Class II | Very high risk |
| ≥ 40.0 | Obese Class III | Extremely high risk |
Here are three example calculations showing how BMI varies across different body types:
Profile: Female, 25 years old
Height: 165 cm (5'5")
Weight: 50 kg (110 lb)
BMI: 18.4
Category: Underweight
Profile: Male, 35 years old
Height: 180 cm (5'11")
Weight: 75 kg (165 lb)
BMI: 23.1
Category: Normal Weight
Profile: Male, 45 years old
Height: 175 cm (5'9")
Weight: 85 kg (187 lb)
BMI: 27.8
Category: Overweight
Note: These are illustrative examples. Your individual BMI will vary based on your unique height and weight.
BMI is one of the simplest health screening tools, but its value depends on context:
Bottom line: If your BMI is outside the normal range, the next step is not panic - it's more data. Check your body fat percentage, measure your waist, and talk to a doctor if needed.
BMI (Body Mass Index) is a screening tool that estimates body weight status based on height and weight. It's used worldwide because it's simple, quick, and correlates with health risks at the population level.
BMI has limitations. It doesn't distinguish between muscle and fat, so athletes may be classified as "overweight" despite being lean. For a complete picture, combine BMI with waist circumference and body fat percentage.
According to the WHO, a healthy BMI for adults is 18.5 to 24.9. This range is associated with the lowest risk of weight-related health problems.
To lower BMI, create a sustainable calorie deficit through diet and exercise. Aim for gradual weight loss of 0.5-1 kg per week. Focus on whole foods and combine strength training with cardio.
BMI for children is calculated the same way but interpreted using age- and sex-specific percentile charts. Always consult a pediatrician for children's weight assessments.
BMI is a simple ratio of weight to height, while body fat percentage measures the actual proportion of fat mass. Body fat percentage is more accurate but requires specialized equipment.