BMI Calculator
Body Mass Index · WHO Standards
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in
lbs
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kg
yrs
Enter your height and weight to calculate your BMI.
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UnderweightNormalOverweightObese
Underweight
Below 18.5
Normal weight
18.5 — 24.9
Overweight
25.0 — 29.9
Obese Class I
30.0 — 34.9
Obese Class II
35.0 — 39.9
Obese Class III
40.0 and above
Healthy weight range for your height: -
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BMI Classification — WHO Standards
BMI (Body Mass Index) is calculated by dividing your weight in kilograms by the square of your height in metres: BMI = kg/m². For imperial units: BMI = (lbs × 703) / (inches²).
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Increased |
| 18.5 — 24.9 | Normal weight | Low |
| 25.0 — 29.9 | Overweight | Increased |
| 30.0 — 34.9 | Obese Class I | High |
| 35.0 — 39.9 | Obese Class II | Very High |
| 40.0 and above | Obese Class III | Extremely High |
BMI limitations: BMI does not distinguish between muscle and fat mass. Athletes and highly muscular individuals may have a high BMI but low body fat. Older adults may have a normal BMI but high body fat due to muscle loss. BMI is a screening tool, not a diagnostic measure.
BMI is a general screening tool. Consult a healthcare professional for a complete health assessment.
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Frequently Asked Questions
What is a healthy BMI range?+
According to WHO guidelines, a BMI of 18.5 to 24.9 is considered a healthy weight for most adults. Below 18.5 is underweight, 25-29.9 is overweight, and 30 or above is obese. These thresholds may vary slightly for certain ethnic populations — some Asian populations have higher health risks at lower BMI values.
Is BMI accurate for everyone?+
BMI has well-known limitations. It does not account for muscle mass, bone density, fat distribution, age, or sex. A muscular athlete may be classified as overweight or obese despite having low body fat. Elderly adults may have a normal BMI but excess body fat due to muscle loss. BMI is a population-level screening tool, not an individual diagnostic.
How do I calculate BMI manually?+
Metric: BMI = weight(kg) ÷ height(m)². Example: 70kg ÷ (1.75m × 1.75m) = 70 ÷ 3.0625 = 22.9. Imperial: BMI = (weight(lbs) × 703) ÷ height(inches)². Example: (160 × 703) ÷ (69 × 69) = 112,480 ÷ 4,761 = 23.6.
What BMI is considered obese?+
A BMI of 30 or above is classified as obese. Obesity is further divided into: Class I (30-34.9), Class II (35-39.9), and Class III or "severe obesity" (40 and above). Obesity is associated with increased risk of type 2 diabetes, heart disease, high blood pressure, and certain cancers.
Does BMI differ for men and women?+
The standard BMI formula and classifications are the same for men and women. However, women naturally carry a higher percentage of body fat than men at the same BMI. Some researchers argue for gender-specific BMI thresholds, but WHO currently uses the same categories for both sexes.
What is a healthy weight for my height?+
Healthy weight is the range that corresponds to a BMI of 18.5 to 24.9 for your height. Our calculator shows your specific healthy weight range. For a 5'9" person, healthy weight ranges from approximately 125 to 168 pounds. For a 5'4" person, it ranges from about 110 to 145 pounds.