Calculate your Body Mass Index (BMI) to check if your weight is in a healthy range for your height.
For your height, a healthy weight is between --
BMI Prime: --
Category: --
BMI is calculated using a simple formula: weight in kilograms divided by the square of height in meters (kg/m²). For example, a person who weighs 70 kg and is 1.75 m tall has a BMI of 22.9. The calculator handles unit conversions automatically when you use imperial measurements.
The BMI categories used by the World Health Organization are: Underweight (below 18.5), Normal weight (18.5-24.9), Overweight (25-29.9), and Obese (30 and above). BMI Prime is a related metric that expresses your BMI as a ratio of the upper normal limit (25). A BMI Prime of 1.0 means you are at the boundary of normal and overweight.
BMI does not distinguish between muscle mass and fat mass. Athletes and bodybuilders often have a high BMI despite having low body fat. It also does not account for fat distribution, bone density, age, sex, or ethnicity. For a complete picture of your health, combine BMI with other measurements like waist circumference, body fat percentage, and regular medical checkups.
The World Health Organization (WHO) classifies BMI into the following categories for adults:
| Category | BMI Range (kg/m²) | Health Risk | Action |
|---|---|---|---|
| Underweight | < 18.5 | Moderate | Increase calorie intake, consult doctor |
| Normal weight | 18.5 - 24.9 | Low | Maintain balanced diet and exercise |
| Overweight | 25.0 - 29.9 | Increased | Reduce calories, increase physical activity |
| Obese Class I | 30.0 - 34.9 | High | Lifestyle changes, medical consultation |
| Obese Class II | 35.0 - 39.9 | Very High | Medical intervention recommended |
| Obese Class III | ≥ 40.0 | Extremely High | Urgent medical treatment needed |
For children and teens aged 2-19, BMI is assessed using age-sex-specific percentiles rather than fixed cutoffs:
| Percentile Range | Classification | What It Means |
|---|---|---|
| Below 5th percentile | Underweight | Less than peers of same age and sex |
| 5th to 84th percentile | Healthy weight | Normal range for age and sex |
| 85th to 94th percentile | Overweight | Above most peers of same age and sex |
| 95th percentile and above | Obese | Significantly above healthy range |
Target weight range for a BMI of 18.5-24.9 (Normal weight):
| Height (cm) | Height (ft/in) | Healthy Weight (kg) | Healthy Weight (lbs) |
|---|---|---|---|
| 150 | 4'11" | 41.6 - 55.9 | 92 - 123 |
| 155 | 5'1" | 44.5 - 59.8 | 98 - 132 |
| 160 | 5'3" | 47.4 - 63.7 | 104 - 140 |
| 165 | 5'5" | 50.4 - 67.7 | 111 - 149 |
| 170 | 5'7" | 53.5 - 71.8 | 118 - 158 |
| 175 | 5'9" | 56.7 - 76.1 | 125 - 168 |
| 180 | 5'11" | 59.9 - 80.5 | 132 - 177 |
| 185 | 6'1" | 63.3 - 85.0 | 139 - 187 |
| 190 | 6'3" | 66.7 - 89.6 | 147 - 197 |
| 195 | 6'5" | 70.2 - 94.3 | 155 - 208 |
| 200 | 6'7" | 73.8 - 99.2 | 163 - 219 |
BMI (Body Mass Index) is a number calculated by dividing your weight in kilograms by the square of your height in meters (kg/m²). It provides a rough estimate of whether your weight is healthy for your height.
BMI is a screening tool, not a diagnostic measure. It does not distinguish between muscle and fat mass, so athletes and muscular individuals may be classified as overweight. It is also less reliable for children, pregnant women, and elderly adults.
For adults, a BMI between 18.5 and 24.9 is considered normal weight. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is classified as obese. These ranges are consistent across most health organizations.
BMI Prime is your BMI divided by 25 (the upper limit of normal BMI). A BMI Prime of 1.0 means you are at the upper boundary of normal weight. Values below 1.0 are in the normal range, while values above 1.0 indicate overweight or obese status.
Yes. Click the Imperial (ft-in/lbs) toggle to switch to feet, inches, and pounds. The calculator converts your measurements to metric internally and shows the healthy weight range in your preferred unit.